Believe it or not, changing your group tag can force your mesh to rez for others. If you're wearing a group tag, take it off and use another one for a couple of minutes. If you're not wearing a group tag, put one on for a few minutes. It was discovered by accident at a very busy club and it works. While your av might be fully rezzed on your screen it might not be for others but changing your group tag will work. Depending on local lag it can take a minute or two.
Before mesh became the next big thing there was one regular at a club I go to whom I could never ever see at all. Not even her name tag showed up, but I could see her on radar. Nothing I did made her av appear for me and I wasn't alone - one of the DJs there couldn't see her either, and he also couldn't ever see one of the other DJs there. Then, suddenly one day she walked in and I could see her. I'm not sure if it was my recent viewer upgrade that changed things, or hers.