When I was in Bangalore, I used to follow the Bangalore Mountaineering Club. They still post pictures on Facebook from time to time so they're still active.
A couple of my friends were in theatre (performance as well as audience). They are very active and I gather Bangalore has a great theatre scene.
My personal vice were rock shows but they seem to have stopped. Iron Maiden, Metallica and Poets of the Fall used to visit frequently. There was always some cover band performing on weekends in one of the christ road pubs.
Another favourite time pass was reading. I would visit blossom once a month at least. My friends tell me they hold reading sessions in gardens in Jayanagar.
Then there's obviously Toastmasters, tech meetups. People keep shaming me for visiting book clubs instead of tech meetups on weekends - to each his own.