The snake-finding vibes worked! We found Roo after a hair-raising 3 hours because my cat was nosing around under the bed. My roomate, now very irked at the cat that let out the snake (that scared the bird that tortured the humans and so on and so on....) scooted her to the side. Or tried to. Phoenix wouldn't move. Audrey grabbed the flashlight and there was Roo, startled but very much okay. A couple tears were shed, more than a few curse words slung, and Ruby is now safe in her tank with an entire semester's textbooks and a pair of platform boots on top of it.
Thank you so much for your help, everyone....and guess who's buying a new tank tomorrow?