Nice job. It could be said that there is and always will be a huge market for Stalking apps. I remember the days of icq/msn where there were apps that shows the who was invisible, who blocked you etc... With the proliferation of API's, social and open web, there will be interesting mashups or even privacy leakages. Something like "find 15km radiuous(4sq) where status is not relationship lookup(facebook) last.fm account whom listens Jazz and employed(linkedin)". Who needs dating services where all information is available?