robg update: Josh has sent in the following modified AppleScript, which is a nicer implementation. Make sure to customize it for your own machine!
set workFolders to ¬
{"Misc", "Bible Studies", "Gradient", "InterVarsity", "Missions", "Guitar Tablature"}
set daysAgo to 15
set recentItemsFolder to "Macintosh HD:Users:josh:Recent Items:"
tell application "Finder"
move every item of folder recentItemsFolder to trash
repeat with counter from 1 to (number of items in workFolders)
make alias file to every file of entire contents of folder ¬
("Macintosh HD:Users:josh:Documents:" & (item counter of workFolders)) ¬
whose (modification date is greater than ((current date) - daysAgo * days) ¬
and name does not contain ".qdfm") at alias recentItemsFolder
end repeat
end tell
[robg adds: I haven't tested this one...]

