HSBC has always been great. They're current interest rate is 5.5%, I believe. Which is more than ING Direct and most of the other "high-interest" savings brokers.
INGDirect, HSBC Direct and CitiDirect are the best 3 IMO. I've used the second and third of these without incident. Heard the same from my friend that use ING too.
bankrate.com is where I go to find the most competetive rates.