Guys, there's no need to use ANY task killer, period.
The way Android works is that it will prioritize processes (apps, games, etc) that you use the most. This way, the OS can manage its resources properly by shutting down the ones you use the least in order to free up RAM for the ones you use the most.
After a certain amount of time, Android will "learn" from you, and you'll notice the apps that remain open are usually the ones you use daily. Also, certain apps (Dolphin HD, Draw Something, etc.) have an exit feature that will shut them down by you hitting the back button (rather than just hitting Home and leaving them open).
*Unfortunately, this doesn't apply to bloat like Verizon Location Agent. Apps like that are meant to run constantly whether you force close or not. If you do force close, they WILL open back up on their own, guaranteed.