I used to spend a lot of money on a game called Wrath of Heroes (which I did guides for last year), where I could buy additional characters to play as. I think they were about £8 a pop and they came out fortnightly, so I spent about £16 a month on them to try them and write about. The other time I spent a lot on "micro"transactions was in World of Warcraft, where every time a new mount or pet came out I purchased it immediately.... only to never use it after a week.
But when it comes to phones, I don't have a smartphone any more so I can't spend my money on cowclickers and whatnot. Good job too because I'd probably go bust in world record times.