OK... today I was fortunate enough to meet Bart Seymour of Implant Nation, and he guided me through the use of one of his mesh avatars, which I bought.
Here's one photo; I'll put up another tomorrow, to honor 1-1-1.
Some things I should point out: first, I had to tweak my shape a bit to make things work. I will experiment to see just what I can get away with and what looks best; I love being impossibly tall and leggy as well as having enormous breasts. (Time to talk with the BIGAVS folks a bit about a REALLY long-legged giantess avatar...) Second, I didn't have a handy skin in texture form to apply to the mesh avatar, so I appear in the photos with a tanned skin. Just imagine I got back from a week on one of the SL nude beaches, OK?
Third, this photo and the one that follows (Bart's; I had just installed the Firestorm FUI beta, and hadn't gotten around to setting graphics) don't show good POV or detail on the mannequin behind me wearing the thong, alas. The stock SL avatar shape is truly bad when it comes to the crotch, and mesh avatars permit a great improvement in that (and other) repsects.
We'll have to see how many clothiers support these avatars. Bart started the clothing layer, which created the market for third-party busty clothing in SL as others followed. I am not sure whether we can move to mesh avatars and have all the possibilities we have with prim breasts (growth or truly extreme size like the royalty of Laurana's Cuties some of which have bustlines well over a hundred feet)--a shame, because sometimes I would love to have my nipples preceding my ribcage by a few meters... but enough of that. Here's today's picture.