The easiest place to put your money with a good amount of liquidity is a money market account. I would recommend ING Direct (ingdirect.com) or Emigrant Direct (emigrantdirect.com). ING Direct has better security and user interface, but Emigrant Direct has a slightly better interest rate (4% APY vs. 3.8% APY).
No minimums, no fees, and the accounts link directly to your bank account. Everything is done online so it's easy too.
A money market account won't make you rich, but will buffer the effect of inflation before you move on to bigger and better investments.
Good luck.