Here's a bookmarklet, based on DeliciousSort, that will sort del.icio.us/popular not just by total number of posts, but by the ratio of recent to total posts. It's trying to automate what I think I do manually, which is to skip the popular items that have been around for a while and only show the new ones.
Works fine in Firefox, but not in Safari (because of the XPath bits, perhaps).
Update: Also looks good with del.icio.us/popular's new sparklines.
Update II: Sparklines have gone, but the /popular page is now sorted this way by default, so there's no need for the bookmarklet.