using text string from a cell to refer to a worksheet tab

hi-
hoping someone here can help me. to lay everything out, i have some historical data organized such that the data for 03-31-08 is on its own tab, 04-30-08 data has its own tab, and so on. then i have a master file which pulls data off of these tabs. my desire is to write a formula such as =SUM('03-31-2008'!E5:E10), but i want to be able to change the tab reference dynamically, so that it is simply referring to a cell (such as cell A2) with the value 03-31-2008, or 04-30-08 or whatever I want to type (instead of being locked static 3-31-08 or whatever). I don't want to have to do a find/replace, I'd like to be ablel to simply change the value of a single cell to the name of one of the other tabs and have everything link off of there.
I have tried to manipulate the text in the reference cell to no avail. Can anyone help? Sorry if this example wasn't completely clear, but it seems like a simple enough thing to do, i just can't figure it out. Much appreciated. thanks

A huge thanks for the help!