Joel Oleson has released a Sharepoint Recycle bin tool.
It sits as an ISAPI filter in IIS on top of the Sharepoint filter. Whenever a user performs a delete action on a document, this filter copies the document to a network share. After the copy action, the Sharepoint ISAPI filter gets the request and deletes the document.
If you install this feature, you don’t have to restore an entire site from backup if anybody has deleted a single file!
Download it here