How does web 2.0 help you save money? Alex Iskold, founder of AdaptiveBlue discusses 3 recent startups that are bound to save you some cash. Farecast, the historical airline ticket pricing site can help you determine if the airfare you are about to purchase is going to come down in price. Mpire lets you track the prices of goods from Ebay, Amazon and Wallmart. Finally Trulia will help you research real estate pricing and you can go further from there. Check the more detailed review here.