I would highly recommend anyone and everyone check out the 4e Turn Tracker software.  It allows players and DMs to track an entire encounter.  You can manage HP, AC, initiative and effects.  As it tracks the turns of combat, it will pick up and drop off the effects naturally as combat progresses.  No more trying to remember if that curse is still active!  Or trying to remember if your players are remmebering their negative effects.  Further, everything is displayed in a nice player-friendly window -- Great for a dual screen set up where the players see one screen while the DM manages everything on the other.  I would highly recommend you at least take a glance at this great attempt at combat tracking!