Windows only: If you're prone to leaving files to linger in your designated download folder and never quite getting around to deleting them, Auto-Delete should be your organization buddy. After selecting a folder to be monitored you can:
You can fine tune the settings to delete files that have been hanging out for a day, a year, or somewhere in between. Files can be moved to the recycle bin or permanently deleted. And you can choose whether to include subfolders or not.
If you're in the market for a more versatile file janitor that can handle more than one folder, check out Belvedere for Windows and Hazel for Mac OS X. Auto-Delete is freeware, Windows only. Auto-Delete [via DownloadSquad]