How about ADA voting record http://www.adaction.org/votingrecords.htm? During the past 5 years Kerry scored 90-95%, except in 2002 when his yes vote on HR 3009 (free trade) HR 4775 (budget caps on discretionary spending) and HR Res 114 (authorization to use force in Iraq) cost him losing 15 percentage points. Not perfect, but not bad either.
For general information: ADA score is computed by examining a representative's voting records on 20 selected bills considered to be a "litmus test" for the liberal political orientation. If a representative votes in line with the liberal position (as defined by ADA) on all 20 of them, he/she receives 100% - a perfect liberal score. The deviation from that position on a vote cost him/her 5% each - e.g. a candidate who voted against the liberal position on 3 bills receives 85%.
ADA scores vary from 0 to 100, but even Paul Wellstone did not always scored 100.
ADA scores are a good indicator of a candidate's political orientation because they are based on his/her actual voting records rather than campaign promises or unrealistic pie-in-the-sky expectations. Thus a high ADA score is a good reason to vote for that person, no?
PS. Anyone who claims that it makes no difference how representatives vote on specific bills needs to have his/her head examined.
Wojtek