I love to browse through the iTunes Music store, even when I'm not necessarily looking to buy right away. This means I always find things I want to buy later. I can't believe Apple hasn't added a "Save for later" feature, but here's something I just stumbled onto:
Above the iTunes Music store window, and below the "Now Playing" window, is the iTunes Navigation bar. If you are looking at an album, it shows the path to where you're at: Home -> Genre -> Artist -> Album. You can drag-and-drop the album name from this bar onto your Desktop, and it turns into a weblink (just like dragging a URL from Safari).
Once created, if you double-click this weblink on your Desktop, it launches Safari and then bounces you to that album in the iTunes Music Store.
[robg adds: There are other ways of doing a 'save for later' in the store. You can select any given song (or use Command-A to select all visible songs) and drag it/them to an iTunes playlist. In the playlist, the songs will be listed complete with the Buy button (and you can hear the preview without opening the Music Store). Another option, which is the one I usually use, is to just add everything to the shopping cart, then review the cart later, before making the purchase decision. Make sure you have 'Buy using a Shopping Cart' enabled in iTunes' Store preferences.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060131191122613