There's a whole slew of them. The main domaining extensions are .in and .co.in.

There's also .firm.in, .net.in, .org.in, .gen.in, and .ind.in.

Then there are specially reserved ones - .ac.in (academic institutions), .edu.in (educational institutions), .res.in (research insitutions), .ernet.in (educational research institutes), .gov.in (government), .mil.in (military), .nic.in (National Informatic Centre).