Ocean Ave has a number of great restaurants & bars offering Happy Hour. Chez Jay is a great local joint with $5 beer, wine & appetizers everyday from 4:30pm-6:00pm. Hotel Shangri-La is offering a new Sunset Happy Hour Friday Nights from 5:00pm-10:00pm. The Lobster has appetizers from $2-$6 or you can get a $2.50 domestic draft or $3.50 house margarita at Rusty's Surf Ranch.
More great Santa Monica Happy Hour options - http://www.santamonica.com/happyhour