Karaoke is awesome.
Courtside
291 Cambridge St, Cambridge - http://www.courtsidekaraoke.com/
Price: Free (Thu, Fri, Sat at 9pm)
Music selection: Huge and many genres, but nothing newer than probably 2002.
Ambiance: Skeezy bar that we probably otherwise never go into. One big communal karaoke room, several big TVs, and a decent sound system.
Alcohol/food: PBR and other urine-flavored drinks, and average pub food. $13 special for a pizza and a pitcher of PBR.
Limelight
204 Tremont St, Boston - http://www.limelightboston.com/
Price: ?
Music selection: ?
Ambiance: Individual rooms
Alcohol/food: ?
Do Re Mi
442 Cambridge St, Allston - Yelp reviews
Price: $30/hr for up to 5, $5/hr per additional person
Music selection: Good (and very up-to-date), according to Yelp
Ambiance: Individual rooms
Alcohol/food: None served
Powderhouse Pub
Powderhouse Square, Cambridge - Yelp reviews
Price: Free, probably.
Music selection: ?
Ambiance: ?
Alcohol/food: ? (It's a bar)