OK money where mouth is time...
Here's the same 2 bar pattern repeated twice, the first two bars is 100% quantized as 16th's with a set velocity of 100, second repeat is the same midi grooved to Nir-Z from a Toontrack midi loop.
http://www.soundclick.com/bands/page_songInfo.cfm?bandID=905939&songID=11926560 It's exactly the same principle at work here as any drum replacement technique where the timing and velocity information is extracted from actual audio of the player enabling a producer to use any sampled sound in place of the actual recorded kit pieces. It's featured on pretty much every hit single that has charted in the last 25 years, so for people to say you can't humanize midi they've obviously been reading too much about celebrated producers from the 50's and 60's.
Sounds pretty good here, huh?
http://www.youtube.com/watch?v=0T0Gpy7nHiM Drums are the most obvious application for it but don't limit yourself to that. It works great on basses too, or any instrument that you want to follow a particular rhythmic groove can have elements of the dynamic sensibilities of any player imposed on them to a greater or lesser degree.
So if you want to humanize first find a human that grooves how you want to groove and you are on your way. If I'm using midi anywhere there's little if any of it that hasn't got a bit of something going on.
I'll even play the groove on the table if I can't get what I'm after any other way then extract the timing and dynamics from that.
So something like AudioSnap, Drum Tracker, Drumagog, (Melodyne?) or Recycle will extract the groove from audio if you don't have any midi grooves available already that will work for you. Then use Groove Quantize, better still Regroove if you are rewired to Reason, to apply it to your own midi to the required degree.
By all means manually edit afterward if you like but it's much easier and less time intensive to do that when you are already in the right ball-park.