The Federal Election Commission (FEC) requires that all campaign contributions over $200 (per donor) be reported publicly. The reported information includes the donor's name, job title, zip code, and even address. All of it, since 2001 is available electronically via FTP at ftp://ftp.fec.gov/FEC/electronic/.
In collaboration with Political Scientists here at BYU we have been performing record linkage (aka. entity resolution) on this data, so that they will be able to more accurately perform their studies.
On a related note, fundrace.org has created an interesting mashup (shown below) that maps donors on a Google map colored by the party or candidate donated to. It also, reveals donor information and appears do do some coarse record linkage.
Additionally, the FEC itself has started to produce maps both for the Presidential Election and House and Senate Elections. The maps they provide aggregate the donated funds by state, party, and candidate.