Firefox only: If you frequently deal with bookmarks that have limited future utility, the Tark (Temporary Bookmarks) extension can set an expiration date on them. For instance, if you bookmark auction listings or some other time-dependent item on the web, only to find you forgot to clean out the temporary bookmarks you'd created, you can attach an expiration date of one week to one month for the bookmarks. At the end of the time period, Tark sweeps them away. Installing Tark does not affect regular bookmarking procedures, and bookmarks that you assign an expiration date can be converted to regular bookmarks at any time. Tark is a free download and works where ever Firefox does.