Yes, IE7 has plugins; they're just called "add-ins." The article covers a couple of ad blockers, a video downloader for those YouTube clips you just have to have, StumbleUpon & del.icio.us add ons, among others.

"Instead, I'll concentrate on lesser-known ones that do everything from killing annoying ads, to restoring crashed browsing sessions, to grabbing video from sites like YouTube and more. Better yet, everyone one of them is free."