Seems a little simpler than automator, but I'm not having good results. I tried out the "new files" built in filter, for example, and asked it to turn all the files that had been downloaded in the last day red. It turned *all* the files red (I have a lot).

Second I asked it to move anything with the extension dmg and older than 1 week to the trash and activated the rule. Nothing happened. Tried "run rules." Nothing. I tried .dmg. Then I changed it to "kind" and chose "disk image." That worked...sort of. Several went into the trash, but there are still disk images in there from June (it's September now).

It does seem to have trashed some incomplete downloads, according to its log, but it hasn't run the rule to empty trash older than 1 month.

Nice interface, though.