That's a wheel bug, a type of assassin bug. They're pretty common around here. They have a pretty nasty bite, so don't handle it. On the other hand, they predate pests, so they're really great to have around, especially in a garden.(At last, my farm entomology class at Virginia Tech is coming in handy!)
We (personally) call them bark beetles - only because they look like bark. We had them in Southern Calif. and here in SW Colorado as well. They are known to have a bad bite- I always use a piece of paper to shoo them out the door. Our puppy once licked one- then backed off and licked his lips for a long time (like after you taste something terrible). When we showed him one to sniff the next day- he backed off fast! SO Apparently they also have a certain yucky taste and scent...Glad to hear there's a good use for them!