Sorry for the very noob question, but I googled for it without finding a proper answer.
What I mean is not moving your wallet from a provider to another, but having multiple different wallets containing different amounts of bitcoins.
Use MultiBit and you can have a quick and easy way to make as many wallets as you want, each completely separate from all the others, and you can sync them all at once and see all their balances at any time, too.
Coinbase is another system like this, and they even pay your fees when sending transactions.