Thanks for your vibes yesterday ladies! I took Max in, and he let them fuss at and poke that skin tag on his paw. The vet's never seen anything like it, but it's most definitely a skin tag and not a tumor of any sort. Since it clearly bugs him enough that he licks and chews at it, they gave us some super antibiotic/steriod cream to (hopefully) heal it up. If that doesn't help, it'll have to come off via surgury. Blah. My poor puppy!
The good thing though, is that he was SO patient last night that the vet said she could do the urgury without putting him under general anesthesia. Seriously, I've never seen a dog stand there and let a vet poke at his paw until it bleeds, and he didn't even try to pull his paw away from her.
Anyhow, so it's hopefully nothing really serious, and with luck the cream will heal it up in the next week or two.