I've been interacting with a few of them recently, and I must say I never thought Telegram would be a hub for mini apps. We have lots of projects building several apps there, like $DOGS, which awards you points based on how long you've been using Telegram.
And then there's $OLYCOIN, which seems to have a connection with the ongoing Olympics and rewards users with Olycoin once you join via their mini Telegram app. You also gain more rewards by referring friends. I'm still looking into many more Telegram mini apps and trying to interact with lots of them.
