DIY Sports Betting is a set of PDF ebooks available on the internet. It was written by Sam Oconnel who is a recreational bettor on a five year winning streak using the information it provides.
It comes with a complete system for the NFL, which is based on point spreads and past performance of certain spread situations. It also has some other useful charts including one for comparing the motivation of the teams playing. On its own this system is very good. After 4 weeks of the 2010 season it has won at 58.3 percent with a 7-5 record in my testing.
It also comes with a similar system for the NBA, also based on spreads. It should produce similar results to those of the NFL system and is comparable in terms of ease of use. Both systems have all of the charts in easy to print files. No wasted time or paper and organization is a breeze.
The main book deals mainly with using the charts in the NFL and NBA betting systems, but it also explains how to build systems for other sports. It all comes down to finding motivated teams in good situations.
It also goes into money management, which is essential to winning. Some of the advice there is a little extreme from an accounting standpoint, but the basic premise is sound. Always bet the same amount on every game, in every sport. No progressive betting, ever.
All in all, DIY Sports Betting is one of the least expensive systems you will find and at the same time is one of the best. It is user friendly, works, and saves a lot of times finding games to bet on.