I've done AKC rally as well as some Cyber Rally-O. It's fun. Rally was originally based on obedience "doodling", or moves designed to help dogs understand different cues and to teach new behaviors. If your dog has a heel, sit, down, stand, come front, and is able to do a finish (go to heel position from front position) to the left and right, then you have pretty much everything you need for at least the first level in pretty much all the organizations that I know of. In some organizations, you may need right side heeling and finishing to your right side in some levels/titling tracks.
The course is designed by the judge, and the organization has rules about how many and what type of stations there are per level. Once you start the course, the judge doesn't give you any further orders. Instead, you are expected to read the signs and perform the behavior(s) shown. Although you are allowed pretty much unlimited communication with your dog, and can use both voice and hand cues, some organizations are more strict on the number of times you can cue your dog ("sit" with both a voice and hand cue are fine, but "sit, sit, sit, sit" while repeated giving a hand cue would lose points).
These are the rally organizations that I know of in the US and Canada:
American Kennel Club
Australian Shepherd Club of America
Canadian Kennel Club (Canada)
Canadian Association of Rally Obedience (Canada)
Canine Works and Games
Cyber Rally-O (online)
International Canine Events Rallye Challenge
Rally Freestyle Elements (live and online)
United Kennel Club
Wag-It Games (live and online)
World Cynosport Rally, Limited