a) I changed my avatar myself. I'm easy enough that if people ask me nicely, I'll do it :-P (hint: Adammon asked nicely).
b) My avatar wasn't a naked chick going down on Santa. It was a clothed girl, sitting in front of Santa's lap. Next you'll say a kid sitting on Santa's lap is giving him a lapdance :-P
c) I surf the forum at work as well, and I googled my avatar there. Yeah, no, unless it's real nudity, I don't hear complaints. About every other page from this forum gets checked by security software either for being "social networking" or "games related", but I've never run into problems due to NSFW content yet. Of course, I stay away from the NSFW forum, and when I log in at work, I disable sigs and avatars.
d) Mav, there's a big difference between *content*, which you can't filter, and belongs either between NSFW and spoiler tags, or on the NSFW forum, and avatars or signatures, which you can easily disable yourself. I won't use something that I consider NSFW there, certainly, but walking the line? If your job is so strict about it that *that* picture would cause problems, you're probably better off turnging off avatars and signatures, since plenty of avatars can give offence in that case. Heck, Sera's avatar would probably raise more eyebrows than mine, at my job.
In attachment my NSF avatar. View at own risk. Do not open this file when children are around. Do not open at work. Do not open in view of your spouse. Do not open when in a public area. Do not open unless completely alone in a concrete bunker 20 ft underground in a remote location. Probably only Sheg can view it safely :-P