Stock springs or aftermarket? Lots of options available, there are anti-wrap leaves:
- http://www.4crawler.com/4x4/4R_suspension-III.shtml#Rear
or traction bars, such as this bolt-on one from Budbuilt:
- http://www.budbuilt.com/new/traction_bars.html
or a DIY version:
- http://www.4x4wire.com/toyota/tech/mini_rearsusp1/
Or things like kicker shocks and traction bars that attach above the top of the springs, etc.

They all work to one degree or another and just depends on how you want them set up.