We got two in Loveland, short but not bad, and they will be extending them soon to connect to Horsetooth - from Devil's Backbone to Rimrock Open Space and on North. I've heard the trail may actually extend beyond that in the future.
I got a buddy who rides up in Horsetooth quite a bit - he's got dozens of routes on trails like Horsetooth Rock trail, Wathan, West Ridge, East Ridge, Mill Creek, Saw Mill, Loggers, Stout, Harrington, Audra Culver, Spring Creek and the unmarked "Cow Path", with extensions into Lory (Nomad, Lower Valley, Upper Valley).
The Horsetooth Lake trail you mention may be Shoreline, which has an extender from Maxwell. There's also trails further down at Michaud Lane (nasty, rocky downhills!)
Those are the ones I know about...there's probably more somewhere...