Supermemo

I think supermemo is a good software for reviewing vocabulary words. I have been using it for the last four years and it helps me a lot in retaining newly-acquired vocabulary. I had added thousands and thousands of example sentences into it over the years. It works like a charm. You can not go wrong as long as you read comprehensible input. So reviewing words in context was a great help for me to own them. My English collection contains 10,500 example sentences (extracted from various resources like books, forums, dictionaries and novels.) BTW, supermemo 98 is a freeware.

You can read more about it at:

http://www.supermemo.com/