For those who haven't found it yet, Trixie looks like a good replacement for the now-dead GreasemonkIE. I have no affiliation with the Trixie project, and found it through Michael's comment. Thanks for the pointer.
I just played around with Trixie a little bit (fixed the google image no-frame script installed with Trixie). It looks like it has the same page refresh bug GMIE had. Maybe that'll be fixed in IE7. The config options are both better (scripts are automatically installed simply by downloading them into the scripts directory) and worse (scripts seem to be stored globally in program files, which won't work well on multi-user systems or with non-admin users; I couldn't find a way to edit includes/excludes without editing the files directly), but at version 0.2.2 it's looking very good.
Congrats to whoever's behind the Trixie project (I'll reiterate, it's not me), and good luck with the project.