WebScanUP is a powerfull domains review and seo stats checker that allow you to collect different SEO statistics like google page rank, alexa rank, whois info and Social Stats like facebook likes, tweets, google plus count and many more stats!
PingClan is a free backlinks creator that you can use to create your own free backlinks creator site in minutes. You also get approx 1900 domains list to ping urls and can add even more easily.
Domain Analyzer PHP Class
NameBot Whois Script
SocialStats PHP Class