well, if they are all xls files, I think you can use Excel to link them all, as ole objects and them edit them that way. I'm not certain, but it's worth a try. I know you can setup your own program to do it too, but that probably isn't what you want to do...
What about using access?
What I would probably do for now, is create a folder with shortcuts to all the files, and then just edit them from there, so you don't need to find them each time.
Just remembered something... We just setup a program called Rational ClearCase, which manages all docuemtns for us. The only problem I can see, a side from cost, is how it manages them. Think of it as a library. You have to check the file in and out, so there is always a tracking key on it. But I think you can group files together, so that you have them as a whole...