I use Google Bookmarks. Any online bookmarking service would probably work, though.

Just make sure adding items is as seamless as possible (I use a bookmarklet). If there's too much friction adding items, you're less likely to do it.

Also, I'll sometimes add certain keywords/phrases in the "notes" field that match how I anticipate I'll try finding it again.

For example, if a Django app uses redis but only for optional features, I'll still add "redis" to the "notes" field. In six months when I'm trying to remember the project, the only thing I may remember is it featured redis in some capacity. From there, it's pretty easy to find.