Quadrant runs a series of benchmarks that theoretically should tell you what is your phone's relative performance to other Android phones. The problem is just how relative is it. In my experience, the CPU clockspeed was given too much weight. Well, at least it's free. There's a paid version, but you don't really need it.
For example, a stock Moto Droid (550 Mhz CPU) rated like 500 or so. When overclocked to 1.2 GHz, the Quadrant rating went up to... 1150. Dualcore CPUs, on the other hand, got almost double. The graphics performance is not weighted that high.
It is okay for some relative performance measures, but don't take it too seriously.
Rating: Try it