Some of your options for tactical or synthetic stocks out there are Hogue, Butler Creek (for a folding stock), and Tapco (for their T-6 tactical with the M4 type retractable stock).
If you are more into the wood stuff for tack driving, there's a bunch out there including Boyd. You can check out Hawk Tech Arms or Rimfire Sports for a good selection.
I bought my BC stock from Cabelas. Cabelas now also carries the Tapco T-6 stock.