Krešo's Arcade
Grab a coffee and crawl some pages.
Noindex Sweeper
Crawl all the pages without hitting a noindex tag. A number tells you how many noindex tags are hiding next to that page. Right-click (or switch the mode) to mark one.
010000
This game needs JavaScript. Ironic, on a site that brags about working without it.
Also hidden on this site: a crawler that walks past now and then (try clicking it, a lot), a free SEO audit (click the visitor counter), and a cheat code from 1986.