I'm just preparing a local Java User Group meeting to take place in a meeting room provided by my employer so that is how this question came up...
Some companies sponsor conferences, some hire open source developers etc but are there any other ways of supporting local developer community?
Offering up your employer's meeting room and taking the time to organize your user group sounds like a good start to me. The user groups I've attended get consulting companies and recruiters to sponsor meetings with free pizza and raffle prizes in return for a few minutes to pitch attendees at the start of each meeting. Beyond that, get creative. Start a website with a forum, invite speakers to talk about new tech, etc.