Some of the places I've been to...
(don't think the following two are in the above link)
Mt. Sanitas: south ridge, lots of bouldering
Mt. FlagStaff: all over the place, just drive up it and you will see...
Eldo (Eldorado Canyon): has bouldering all over too, too many to describe, use link above or Google. It has a $5 entry fee or so as it's a state park.
All over, but Lumpy Ridge, north of Estes Park, besides its obvious climbs, also has a lot of bouldering opportunities if you just go for a hike.