I am a huge fan of ING Direct and have been for a long time - I joined in June 2001, the summer before I left for college, and my first account was named the "oh shit fund". (It is still called that.)
Well, I am now up to six accounts with them, having opened an Electric Orange account a week or so ago, and yesterday opened yet another savings account in order to hold my credit card payoff money. I have about $5700 on a 0% balance transfer and decided to just save it up and hang onto the money until it expires next December to earn a little more interest. Once it's paid off, I may start doing some 0% balance transfer arbitrage stuff to earn more, but we will see. But to keep that money separate, I opened another account. You can open as many savings accounts as you want under one customer number, and give them all different names, and they will have different account numbers so you can direct deposit into specific accounts. So right now I have my "oh shit fund", a house fund, a credit card holding account, an Electric Orange checking account, and two accounts for CashDuck which hold tax money and business savings. This should be enough accounts for me in a while.. I just do so love to have every dollar in its place!