Based on the size, its most likely a juvenile which makes IDing it nearly impossible.
I personally think that it is a spider (best guess http://www.insectidentification.org/ins ... rab-Spider
1) spiders have 2 bodyparts a head and an abdomin. I don't see a thorax.
2) a spider's legs will erupt from the smaller bodypart (the head)
3) you found it on a wall, its not an ant and doesn't have wings. thats not a smoking gun, but I definitely smell sulfur.
4) it is brightly colored, which is uncommon among non-predatory insects
5) I don't think my crab-spider is a bad guess really... at least based on the photo. crab spiders don't use webs, they hunt basically like crabs do, which also means walking funny and waving their front feet around like antenne.
6) chigger is also a perfectly acceptable (if a little boring) answer. i feel like its too big for that though.