In the old days, back when bank accounts, CDs, money markets and even checking accounts actually paid interest, I used to play the games I was forced to play to get as much interest as possible on cash. These days, however, it seems like playing that game is like winning at a loser's game. So, for the most part, I just keep spare cash in the checking account - no noticeable interest (hey, no 1099's either, heh, heh). I have access to my 401(k) and at 2 days notice if I need a chunk of cash, I just hop on-line and transfer to the checking acct. Yes, they keep 20% for the gummint, but it's quick and I do get over 2% right now in my stable value fund (whoooopieeee!)
DW and I did the I-bond thing this year as well, though I doubt I'll mess with that in 2012 since it will all be on-line and I like the bonds in my hot little hands.
Slightly off topic, but one reason to carefully manage cash is to keep inflation from ravaging your cash savings value. Realistically, right now, one could make a case for using some spare cash to purchase things they will need within the next few years and then store them - It's a PITA, but no one is likely to steal your extra bails of TP or industrial size cans of tuna, but you WILL equal inflation with such a strategy. AND, you don't get charged taxes on the gains!! Naturally, YMMV.