From the Finnish Business and Policy Forum: http://www.eva.fi/eng/index.php?m=2

"The report emphasises that in a diverse society it is not prudent for all support to be channelled via the general government budget and distributed merely via the political system. Pluralism and diversity are best promoted when financing coming from many sources.

Contrary to the case in Finland, most Western European countries' legislation encourages donations. Besides Finland, the tax deductibility of donations by private persons is lacking only in Sweden and Spain. The tax deductibility of donations by corporations is limited more tightly than in Finland only in Sweden.

There is currently no ceiling for corporations to deduct donations intended to preserve Finnish cultural heritage. Donations to promote science and art can be deducted up to 25,000 euros per recipient. The recipient of the donation can be the Finnish government, a Finnish university or Finnish organization, institution or foundation designated by the tax authorities.

In the report it is deemed likely that the low ceiling per recipient for deductibility of donations reduces the total amount of donations. In Great Britain, where there are no ceilings per recipient on donations by corporations, large companies have donated 0.5-0.6 per cent of their profits before taxes for charitable purposes. In Finland the corresponding share would enable the funding of 50 permanent professorships.

Companies can deduct their sponsorship costs as a marketing expense, the same as research and development costs related directly to their business. On the other hand, the report points out that company support for basic research, which creates the basis for the next generations of products and services, is not ordinarily deductible as an expense. "

You can't be me, I'm taken

In France, state pays some money to parties with elected members (but given the voting system it's hard to get those).

For donation, only people can give to parties and not corporation (to my knowledge).

Up to 7500 euros per person per year is eligible for tax deduction of 66%, it means that if you pay enough taxes, state will pay you back 0.66*7500 = 4950 euros, so real cost for you of a 7500 euros donation is only 2550 euros.

And I just wrote a 7500 euros check to Segolene Royal campaign association :).

Campaign spending by parties is controlled too (accounting controlled by the constitutional court), looks strict (elections do get cancelled) but I don't know the exact rules.

Ley Organica 3/1987, de 2 de julio, sobre Financiación de los Partidos Políticos		Organic Law 3/1987, of July 2, on Funding of Political Parties
TÍTULO II. FUENTES DE FINANCIACIÓN. CAPÍTULO II. FINANCIACIÓN PRIVADA. Artículo 5.		TITLE II. SOURCES OF FUNDING. CHAPTER II. PRIVATE FUNDING. Article 5.
Uno. Los Partidos Políticos podrán recibir aportaciones no finalistas, dentro de los límites y, con arreglo a los requisitos y condiciones establecidas en la presente Ley.		One. Political Parties will be able to receive contributions without earmarking, within the limits of, and according to the requirements and conditions established by the present law.
Dos. Las aportaciones procedentes de personas jurídicas requerirán acuerdo adoptado en debida forma por el órgano social competente al efecto.		Two. Contributions from legal persons shall require an agreement adopted in due form by the social organ competent to that effect.
Tres. No obstante lo anterior, los Partidos no podrán aceptar o recibir, directa o indirectamente:		Tres. Notwithstanding the foregoing, Parties will not be able to accept of receive, directly or indirectly:
1. Aportaciones anónimas, cuando la cuantía total de las recibidas en un ejercicio económico anual sobrepase el 5 % de la cantidad asignada en los Presupuestos Generales del Estado en ese ejercicio para atender la subvención pública a los Partidos Políticos prevista en el artículo anterior.		1. Anonymous contributions, when the total amount received in a financial year exceeds 5% of the quantity allocated in the National Budget for that financial year to attend to the public subsidy of POlitical Parties provided in the previous article.
2. Aportaciones procedentes de una misma persona física o jurídica, superiores a la cantidad de 10.000.000 de pesetas al año.		2. Contributions from the same physical or legal person, exceeding the amount of 10M pesetas [€6k] per year.
3. Aportaciones procedentes de empresas públicas ni de empresas que, mediante contrato vigente, presten servicios o realicen obras o suministros para alguna Administración Pública.		3. Contributions from public companies, or from private companies which, by a contract currently in force, provide services or make works or supplies for any public administration.
Artículo 6.		Article 6.
Uno. Los Partidos Políticos podrán recibir aportaciones no finalistas, Procedentes de personas extranjeras con los límites, requisitos y condiciones establecidas en la presente Ley, y siempre que se cumplan, además, los requisitos de la normativa vigente sobre control de cambios y movimiento de capitales.		One. Political Parties will be able to accept non-earmarked contributions, from foreign persons with the limits, requirements and conditions established in the present Law, and provided that, in addition, the requirements are satisfied of the norms currently in force regarding control of currency exchange and movement of capital.
Dos. No obstante lo anterior, los Partidos no podrán aceptar cualquier forma de financiación por parte de Gobiernos y organismos públicos extranjeros, sin perjuicio de las subvenciones de funcionamiento establecidas por el Parlamento Europeo.		Two. Notwithstanding the foregoing, Parties will not be able to accept any form of funding from foreign governments or public organisms, without prejudice of operating subsidies established by the European Parliament.
Artículo 7.		Article 7.
El importe de las aportaciones a que se refieren los artículos 5 y 6, se abonará exclusivamente en cuentas de entidades de crédito, cuyos únicos ingresos serán los procedentes de las mismas.		The amount of the contributions referred to by articles 5 and 6 shall be paid exclusively into accounts with credit entities; the only deposits into these accounts shall be those resulting from the said donations.
Artículo 8.		Article 8.
El incumplimiento por los Partidos Políticos de las prohibiciones establecidas en los artículos 5 y 6.2, será sancionado con multa equivalente al doble de la aportación ilegalmente aceptada.		The infringement by a Political Party of the prohibitions established in articles 5 and 6.2, whall be sanctioned with a fine of twice the amount of the illegally acecpted contribution.
Artículo 9.		Article 9.
Solo podrán resultar comprometidos por los Partidos Políticos hasta el 25 % de los ingresos procedentes de la financiación pública contemplada en los apartados b y c del artículo 2.1, para el pago de anualidades de Amortización de operaciones de crédito.		Political parties shall only be able to commit up to 25% of the income coming from the public funding contemplated in sections b and c of article 2.1, for the amortizing of credit operations.

The English translation is mine, and therefore not authoritative.

Those whom the Gods wish to destroy They first make mad. -- Euripides

Here is Colman's original story: What power do we have? by Colman on August 3rd, 2005

Those whom the Gods wish to destroy They first make mad. -- Euripides