I've decided that I'm going to force myself to use all of the RPG books I've stockpiled and never touched. I suffer from gaming ADD; I hear about an interesting new book, buy it, read it, get psyched to run it, and then something else catches my eye before anything materializes, resulting in nothing ever getting played. That cycle has repeated itself for about 15 years now. I now have several complete gamelines that have never been used. In the case of Star Wars, I have a complete gameline that was never used, and has been obsoleted by a new Star Wars gameline that I own and have never used. I think that sobering realization was the straw that broke the camel's back (well, that and my g/f asking me at Borders why I'm always buying RPG books that I never end up using).
We recently had fun trying out the new Warhammer Fantasy Roleplay 3rd edition (with Lio as a Troll Slayer and Action Widow as a disgraced Wood Elf Thief), and we're getting pretty comfortable with the new system. Next we're trying out Shadowrun 4th edition (which I own every book for and have never used). After an adventure of that we'll try out something else. I do plan on getting back to WFRP3 though, because I really like Lio and Action Widow's characters, and I've got some solid ideas for a long-term campaign. Lio's Troll Slayer (Olaf Runebreaker) is nursing a fallen dwarf back to sanity (when he's not beheading greenskins or trying to create a Dwelf), and Action Widow's Elf (Moonthistle) is seducing haggardly peasant cooks while developing various con-jobs and poison-crafting skills.
Aside from forcing us to finally make use all these books, this approach serves a few other purposes. It gets us comfortable with the rules for all these different games, which makes the prospect of playing them in the future far less daunting. Also, we'll start to figure out which games we really like, and which games we don't; I suspect there are games that we buy books for and wouldn't even enjoy (if we ever got around to playing them).
I think the major benefit, however, is getting comfortable running these different games for our monthly gaming weekends (which I really hope we get going again, because that weekend at Stone's place in Boston was fucking awesome and I miss having us all together). It'll be much easier to get a variety of games going if Lio and I are comfortable running them, so that the burden doesn't always fall on Stone and Calliander to run D&D. I'm envisioning a setup where we get several different games going at once, riffing off each other and trying lots of new stuff like back in the day.