Copying a successful business plan is safe, and tons of companies are copying Groupon. The differentiating strategies of the more successful copycats are interesting, as is the arms-race and recursion of deal aggregators. I find it fascinating that people sign up for this stuff, because I find it wasteful. This is insane: “In just over two years, Groupon has accumulated 60 million subscribers, more than $1 billion in venture capital and $760 million in annual revenue to become the fastest-growing Web company ever. In December, it declined a $6 billion buyout offer from Google.”

Customer service done right.

It takes time and a lot of guts, but you'll save money. "It really works... but it works only if you truly are willing to walk away... and then refuse to bend when they try to put you off or change the terms. Stay civil, do not let any emotion in."