Casino Verité: ($90)
This product is the ultimate in blackjack practice software. With more features than you can even imagine, this program will let you practice card counting and playing in a very realistic environment. In addition to practice, there are drills, tests, and a variety of useful calculators included.
MGP's Blackjack Combinatorial Analyzer: (Freeware)
This free software for Windows lets you do accurate analysis of any set of rules for blackjack. It provides optimal strategies, expected value of every decision, and much more. Thanks MGP for releasing this tremendous tool as freeware.