I enjoy good wine and after several years learning about wine I think I know something about it. But I've gotten lazy and stopped taking notes about the wine I drink. It just seemed too much like work.
When we were in France we had a lot of great wine, mostly from the Southwest: Bergerac, Cahors, Languedoc... But since I don't know the wines there I can't remember what we had. The only wine I thought to write down was a Languedoc, a 1995 Domaine de La Grange des Pères that was fantastic. But specifically how was it fantastic? I can't tell you now.
Maybe my friend's manageyourcellar.com is the solution. It's a web application for tracking your wine cellar and tasting notes. The views of your own cellar are nicely customed: "ready to drink", statistics, recommendations. A nicely detailed database of wines holds it all together. The site has a wine blog too. Now to get some discipline about keeping notes!
Inspired by this Ask Metafilter thread