Survey USA is not only a great polling firm; they're also great about openly comparing their results to others. Today, they released a comparison of 2008 pollsters' average error per race.
Not only has Survey USA polled the second most races (to Rasmussen), they also have the lowest average error.
Here's their rankings of "active pollster," which they seem to define as pollster's that have polled at least 4 races this year.
And here's the breakdown:
The biggest misses so far seem to have been the New Hampshire, South Carolina, and Georgia Democratic primaries. Survey USA sat two of those out, so they gain an advantage there. Rasmussen was the only polling firm to include all three.
They also have chart comparing all pollster from 2008. The Field Poll tops the list, which is a bit troublesome since their California numbers (the only race they polled) had a ton of undecideds because they didn't push leaners. Survey USA seems to push leaners more than most other polls, which makes their accuracy even more impressive.
What I particularly like about Survey USA is that they provide full crosstabs for each of their polls.
Here's Survey USA's lifetime comparisons versus other polling firms (ranked by number of contests both firms polled on:
They have several different ways to measure lifetime scores, and they give you the ability to sort this list by each of them.
Survey USA does a lot of state general election matchups, and I hope people take them seriously going forward.