The Tools for Thought blog has a thoughtful post tackling the problems many would-be followers of Getting Things Done have with the Someday/Maybe list, where you (supposedly) place realistic things you just can't get to right now. Many lists are ignored, for example, because they're just too darn long.
A good trick in reviewing the list is to scan it with the question in mind, "What can I get rid of?" Even if you don't get rid of anything some weeks, you'll find that you pay more attention to the process. You might want to create a next action to edit the list as thoroughly as possible. Consider putting some items that you'll still think about occasionally but not every week in a less frequent queue, either on your calendar or your tickler file.
How often do you get back to your Someday/Maybe list, and what practices help you keep it in check? Tell us about it in the comments.