Shape Up
Really good book.
Basecamp did a good job exposing their workflow and process.
Some things suggested will work just for experienced teams with mature communication, if you don't have a team that normally shares early, you'll probably fail badly trying 6-week cycles. The same can be said about a shape-up - hands-on cycle, it will only work well after some size, if you have a small team (less than 20 or 25 people), it will only add unnecessary overheads.
It has some process definitions I've never noticed even working with the product for a while; uphill and downhill as progress phases will be really useful in the future. It also contains important tips for product managers who don't have a tech background, such as: keep the right abstraction level, so you don't make things too open, nor create an environment where things are so well tied that developers/designers have no room for creation, and give room (as cycle or time between cycles) for the team to work on purely technical tasks.
The last and hardest thing to master is how they really make a bet on the project, if nothing is done when time ends they call the next bet. It's risky but probably really efficient in a way people don't become too involved with the ideas and they know how and when to cut something from the scope, because delivering something is better than delivering nothing. This is something to practice, maybe softly but it is an excellent room to test.