While there is no perfectly functional Ice Cream Sandwich ROM for the HTC EVO 4G yet, we keep creeping a bit closer with each day to the point where we'll have a fully usable ICS daily driver. The Android Open Kang Project has pieced together a very stable offering for the HTC EVO 4G that I'd consider a strong candidate.
I'll start with what doesn't work: video recording, 4G, Netflix, Chrome, and front-facing camera. If you can live without these things, then you should be pretty happy because as far as I've been able to tell so far, everything else works right out of the box.
This is the snappiest, most responsive, most customizable, and most stable ICS ROM I have ever seen on my EVO 4G, and if it were available for my EVO 3D (and worked with Chrome/Netflix), I'd be running it as my daily. It also boasts, hands down, the most unique loading screen I have ever seen.
As other ICS builds out there have the ability to run Chrome (such as Deck's Alpha 6), hopefully we'll see it in Team Kang's builds soon enough too. The Netflix/Chrome problems evidently stem from hardware acceleration issues.
This is the most full-featured and stable ICS I have run across yet, it's well checking out if you're looking to play with a very well designed product.[RootzWiki]