First, thanks a lot for the great work you guys are doing. I can't imagine working without RStudio!
One thing I'd really like to see in the IDE is a search history; that is, being able to cycle through recent find / replace strings. I recently found myself having to do global search&replace for a bunch of scripts with a regular expression, and copying the find and replace fields from one document to another was really tedious (I ended up doing it in notepad++).
Another possible approach would be to retain the last find/replace values across scripts, and also not "clear" them when the search "toolbar" is closed.