first that comes to mind is the Anthill Pub on UCI's campus near the student center. I work down the street and often stop by for a liquid lunch. The first time I made a visit I was pleasantly surprised by the selection. You wont find Coors or Bud in this place. A heavy selection of ever rotating micro and craft brews, including Pliny the Elder. Last I was there a 10oz glass of Elder was $4.50. Also, they are known to get Pliny the Younger and will not advertise it. By request only. Great, low cost diner food as well.
I know where I'm heading for lunch today.
Check out The Bruery in Placentia. Outstanding Belgian style brews, great people who work there, and they usually have food trucks outside that serve some great food. Every Sunday the Lime Truck makes an appearance, and I'd have to say that their food is better than most restaurants.
Right now The Bruery has an outstanding porter on tap that will become a regular release for their retail store in Orange.
Bootleggers in Fullerton is also very good, they are new so the tasting times are a bit limited
The Bruery makes solid beer for an O.C. brewery. They're open until 10pm on Fridays and Saturdays, have a beer sampler deal that lets you keep the glass, and normally has a gourmet food truck outside until closing (on those 2 days only).