For some fun, sandbagged 5.7-8 fun, make sure to do Ruper in Eldorado canyon, and also Cussin' Crack on Castle rock in Boulder Canyon. Cussin' crack is probably the hardest 5.7 I've ever climbed, I was totally sweating and pumped. Huston crack on Cob rock in Boulder Canyon is also great.

For some harder routes do Grandmother's Challenge (10c) in Eldo (overhanging!). Really airy and fun if you don't fall.

The Acrophile in South St. Vrain, has a wide overhanging section, but it might be more in the category of wide cracks that require some offwidth technique.

I betcha everything mentioned so far on this list (well, at least those with legal access) gets more ascents than On-Slot up at Continental Crag in Eldo.

On-slot is really good, but if I remember correctly, you can avoid the offwidth at about the same grade. The route is definitely worth doing.

Went up to Bacon and Ergs on Sunday. Awesome line, but man did I get worked. So far, the hardest OW I have found in Boulder County. The approach is kind of long to make it a "proj" so I hope I can toughen up and send it before all of the hiking up there makes my quads too big to fit in the crack.

Thanks for reminding me about On-Slot. Also, I remember there being a three pitch route near Tunnel 7 that has an OW finish. Has a funny name.

I thought Funeral March was a bit of a pile. It's on the list now, anyway.

Buildings often have good training offwidths. If you climb one very day eventually they will start to seem reasonable. Is there anything on the CU Campus?

There is a buildering problem we call Blockbuster Offwidth in the shopping center at Arapahoe and 28th.

I've heard of some sick stuff in the Macy's parking garage, too.

Some flatirons Offwidth not to miss (though some have seasonal closures:

Electric Fountain Crack (tough 5.8)
http://www.mountainproject.com/v/colorado/boulder/flatirons/>>>>>
And while you are tehre- run up Yoni (5.6)
http://www.mountainproject.com/v/colorado/boulder/flatirons/>>>>>

I don't know whose hands fit in 'Handcrack; but he musta been big:
http://www.mountainproject.com/v/colorado/boulder/flatirons/>>>>>

The top of Euclid's Corner (5.10) is a wide diversion- check out those photos of Chris through the crack:
http://www.mountainproject.com/v/colorado/boulder/flatirons/>>>>>
Arm bars, heal-toes, chicken wings... and the dreaded headjam...

Like it steep? How about going 'Under The Influence' (5.11):
http://www.mountainproject.com/v/colorado/boulder/flatirons/>>>>>

Devil's Plaything (5.10) has some excellent wide crack on it in spots, though it is not consistent:
http://www.mountainproject.com/v/colorado/boulder/flatirons/>>>>>

Off Width Her Head (5.8+) is well named:
http://www.mountainproject.com/v/colorado/boulder/flatirons/>>>>>

If you went and did the last 2 of these, it would probably be the second ascent! I sincerely doubt more than a few ascents of 'Under The Influence' have been made either.

This is a great list of offwidths you guys are compiling. Most of them I've never heard of. Euclid's Corner, on the other hand, cannot be considered an offwidth in my opinion. The upper overhanging section is wide for sure, and spectacular, but if you climb it right side in you're pretty much lying on your back. I bet it feels (and looks) harder climbing it like Tony's second in the photos. I am NOT a strong offwidth climber and the wide part of this pitch felt number grades easier than the thin-corner-crack business on the lower part, and required no offwidth techniques. Just my two cents..........
While we're straying so far from the "Boulder area", what about Road Warrior on Evans? Not a winter route, but seemingly one of the best lines of multi-pitch wide crack goodness in the state. I've gotta get up there this summer..........

Crack of Fear lives up to it's name as it's scary. Road Warrior is not. Apples to Oranges.

Another 'easy' route is Osiris, on the book at Lumpy Ridge. Only given 5.6, the first pitch is wide the whole way with some smaller gear placements. It looks like you can layback it, but it only works in a few spots. Lots of arm barring and chicken wing type moves. The grade is easy, but the route would freak out a new leader (most likely).