having had an iphone and now got an android
i would say the most useful app ive used on both especially for dating is
'Around Me'
it ties into google maps -- so say you tell some chick you are gonna meet her at such n such a bar in a strange city/town whatever-- you go park up somwhere near
go through bars and select the bar name in the app and it directs you on google maps to it
also really useful if you think- shit i need a chemist, it will find and take you to the nearest one
i love it anyhow