If you need a heat wrap for fermentation, check out Reptile Basics.com. They have 12" tall "heat tape" for $3/foot as well as the extension cord & connectors ($4; add .99 if you want them to connect the wire to the heat tape). I got two 2 footers with the cord and had them connect them (basically a Fermwrap) for $21.98 ($6.99 shipping). A Fermwrap is about $35-$40 so I got 2 for less than the price of 1. You can wrap it around a carboy and control your fermentation temp with a temp controller.

The wrap I bought is 24" long so it doesn't completely wrap the carboy. However, I've found that is not necessary. The idea is to warm the beer in the carboy to a given temp (provided you're using a temp controller and have a way to also keep the beer in a cooler environment). I tape my controller's (insulated) probe to the carboy in the space between the ends of the wrap. It works very well, same as a Fermwrap. It's possible to keep the beer within about +/- 1 degree.