My wife is in a cover band that gigs several days a week. As I've heard the music many many times (I enjoy it, just used to it), I don't drink or dance, and I've never been much of one for watching a band, I end up doing work on my laptop. So this means I'm often working at a bar, club, restaurant, wedding, or on a large boat/yacht (such as for the Eastbound & Down wrap party last year).
As long as I'm able to find wifi or otherwise tether on my phone, I'm surprisingly productive considering the venues :-)
To avoid annoying venue patrons w/ bright light in dark room, I tend to find a place out-of-direct-view, ideally w/ laptop light hitting a wall, and brightness turned way down. If I'm close enough to the sound guy, people often then I'm running sound or lights :-D