I came across this today, TidyPlates, and it’s a great replacement to the periodically maintained, hard-to-configure Aloft. Note the version on Curse is older, so install it via wowinterface, not the Curse client.
Name plate mods help you know up who you have threat on, and who you’ve lost, and should be designed to reduce visual clutter. TidyPlates has modes which are tuned to tank, dps or pvp usage, and I found the tank settings ideal. It’s also lightweight, so it should have no CPU or FPS hit.
It is also skinnable, and there are loads of themes you can try. I found the default theme and tank mode fine for my purposes, so didn’t need to customise at all. That said, there is one specifically for tanking which looks good since it shows degrees of threat.
Update, a few hours later: Kadomi just published her own review of this, and she recommends that skin… I’ll have to go try it now.