Amongst a host of others, Flock realizes an idea I had a while ago and told Google about: a real simple way to remember a site. In Flock, it's called to "star" a site. Very quick. No folder selection. And with full text search. This is exactly right. Because at the moment I am starring the site, I am really ready to move away from it again. I don't want to bother with classification. When, later, I look for it again, I will probably remember enough about it so I can find it using the history search.
My own idea went like this. I was going to create a small extension to Firefox that would, at the press of a hotkey, add the current page to my "trail", a list of tagged pages. This list I would periodically upload to a publicly reachable web server in a very special format. All the link texts would contain a unique number assigned to me (a GUID probably). Then I would submit the list to Google for reindexing. When, later on, I need to search through my trail, I simply send a search request to Google with the special condition that only pages linked to from links with this unique number in the link text are to be searched (this is a feature of Google's advanced search, configurable in the "Occurrence" setting). Neat, huh? But embedding Lucene in Flock is, of course, even better, although it does hog my disk space instead of Google's.