After a simple tool to track initiative, health and defenses during combat in 3.5e or 4e? Then Trackwork is an app you should take a look at.
Version 0.4 wasn’t very 4e-friendly, so I’ve made some updates to the code and v0.5 is very happy to accept all your 4th Edition needs. The interface had to be reworked to accommodate fortitude, reflex and willpower.
If you have Vista, you’re all set. Everyone else, be sure to grab the .NET Framework 2.0 if you don’t have it.
Update #1: Uploaded a minor revision to allow HP, AC, Fort, Ref and Will to accept up to 9999 as a value (thanks Granger44).
Update #2: v0.5b is up. You can now import a fight. This lets you save your heroes in one file and the encounter in another, and then mix them together when the combat starts.