counting independent sets What algorithms/mathematical techniques are available to exactly/approximately count number of independent sets?

Is/Are there a good reference/good references on this topic?

I am interested in regular graphs.
The problem can be restated as a #2SAT. See 

http://en.wikipedia.org/wiki/2-satisfiability 

under the "Counting the number of satisfying assignments" section for some references to the currently best exact counting algorithms.