Gomez Advisors
Well organized. Offers multiple evaluations of brokers including price, service, reliability and more. User may select trading profile and choose broker that matches profile.

Sonic.Net
Continuous tracking and evaluation of brokers. Posts user comments about individual brokers. Ranked by price norm - but also significantly below those offered by other discount brokers.

Top Ten Links
Online voting for top brokers. Easy to read, links to brokers.

Please send news of other comparison resources. Thanks!