I've got a Nexstar 102 SLT, and I agree that it has some stability issues! I got
this dovetail bar and
these rings (obviously you'd have to get the right size rings), and they do certainly help. They also allow me to balance the scope properly with all that 2" stuff on the back!
I should mention that I installed the rings and dovetail bar without having to modify the OTA at all. The original dovetail fits underneath the new one without any modification, so I haven't voided my warranty or risked the optics by fiddling with screws, and I didn't have to rotate the scope (which would have put the finder in a weird spot).
This electric focuser is probably the best upgrade though, because you can completely eliminate the shakes from focusing. No longer really cheap I guess, but it's a highly recommended piece of gear!
The main area of instability remaining for me is actually in the tripod, and then the mount. The mount (AZ in particular) I can't seem to fix, but I'll keep trying. As for the tripod, it has silly plastic caps connecting the legs to the top, and these allow a lot of twist. I fixed that by digging out an old heavy duty aluminium photographic tripod (which is quite sturdy and stable) and using that in place of the stock one. I had to make an adapter so it would fit, and I had to use the whole top of the stock tripod, just with the legs removed.
Anyway, it's now a lot better, but I still feel the wobbles! Below is a photo (before I changed the tripod), also showing the weather, now that the scope is ready for action!
http://imageshack.us/a/img23/1096/img4067dxo.jpg