I haven't been guilty of this for quite a few years, but I'm kicking around the idea of doing so now. After worrying so much about balance, I'm ready to just give the players the keys to the candy store, then unleash the hordes on them. It should be a nice change of pace.
/hijack alert/
BTW - I'm considering using the old Giants and Descent into the Depths modules for this purpose, given how much tougher they are in 3E. Has anyone run these with the new rules? I'm curious how it went.
/end hijack/