I know some of you are against the dashboard with nothing short of a religious fervor. I actually like it. I don't use it often but I find a few widgets very helpful including iStat, the Birthday Reminder, and (of course) Chuck Norris Facts. There are others I like but I'll save that for another post.
Anyway, if you are really worried about the Dashboard taking too much of your system memory there is a widget called Dashquit 2.0 which gives you a quick percentage of exactly how much memory you are using with your widgets and by pushing one little button on the widget it closes down dashboard and dumps them from memory. If you are about to dive deep into GarageBand or do something else memory intensive, you can free up that memory with one click. Below is a screenshot taken of my Dashquit at the the time of posting.