We've been using Cow Sense since 1993 and really like it. Cow Sense archives all of the animals that have left the herd, from death to cull to sent to the feedlot with disposal codes, so we can still look up those animals. I can send registration info into the associations easily.
We can enter anything and everything we can think of on the animals (carcass data, preg check info, color, etc.) and can make reports based on certain items. For example, I can search for calves born in 2011 with a BW less than 80lbs and a weaning weight over 600 lbs and a carcass weight of greater than 800lbs and have a list of those calves. I can do the same with cows and bulls, and we actually use these reports to make culling decisions because they're so powerful.
We can keep track of breedings, and it will store all previous breeding also, and calculates estimated calving dates (for both natural and AI). It also allows you to enter EPDs and make breeding selections with those.
We have their Sale Manager program to keep track of buyers and buyer purchases as well as enter sale info, but the Cow Sense program lets you enter sale dates and sale prices too. And we use their chute-side program when weighing (records weights automatically when the laptop is connected to the scale) and preg checking to record data.
The only complaint is that it's a little overwhelming at first to get used to it, there so much you can enter and do with it. But like anything else, the more you work with it, the easier it is.