tinder, PoF, facebook occasionally (not installing that messenger app though)
tasker can be used to create an auto-liker for tinder, as well as automating pretty much anything on android

I've installed snapchat but not set it up, might have to get round to that if I'm missing boobies

I use myfitnesspal intermittently to track calories, and endomondo to track my lunchtime walks/runs

kindle, originally installed as I had a free trial of prime, and wanted to 'borrow' Manson's 'Models' I've found a few free books I am enjoying, might eventually give them some money

other 'off topic' apps I swear by include gStrings (really accurate free guitar tuner app), realcalc (scientific calculator), XBMC remote to control my media centre, and quickoffice for taking quick notes/spreadsheet calculations