Google Checkout is kind of like PayPal without all of the hassle...you'll be seeing a lot of online vendors large and small start to adopt it over the coming year..
Google has a ton of different optimization tools for webmasters, including Google Analytics:
Google Analytics
Also there are third party optimization software available, like the CoffeeCup Google SiteMapper which I recently purchased (but haven't really had the chance to use yet)
CoffeeCup Google SiteMapper - Create Powerful Google Sitemaps in Seconds!