Update: The party's over! They've dropped the rate to 3.55% APY on 3/20.

Washington Mutual Bank is probably the most widely known bank that offers competitive rates, currently at 4.00% APY Online Savings when you sign up online for a WaMu Free Checking account. Minimum balance to open Online Savings is $1. They also do not charge you for ATM withdrawals from non-WaMu ATMs.

WTDirect.com - Wilmington Trust Direct is offering a 3.91% APY for the first 60 days from the date the account is opened, regardless of the account balance. Thereafter an account balance of $10k is required to stay at that rate. FDIC-insured up to $100,000 per depositor with Wilmington Trust FSB.

HSBC Direct offers 3.55% in their online savings account. Minimum balance to open is $1. If a third party charges you to use their ATM in the U.S., HSBC will rebate up to three of these fees based on transaction date order during the calendar month.