Amoeba Berkeley will celebrate its twentieth anniversary this weekend, Saturday and Sunday, Nov. 13-14, with a special sale and events. Select titles will be on sale on Saturday, then on Sunday, there will be a store-wide 20-percent-off sale on its used CDs. Sunday will also feature in-house music courtesy of The Coup’s Pam the Funkstress, DJ Platurn of the Oakland Faders, Foxtails Brigade (busking throughout the afternoon inside and outside the store), and Lyrics Born (free, all-ages set at 5 p.m., followed by CD signing). Pick up a gift bag if you spend more than $20, win a raffle prize, and chow on some birthday cake. Amoeba is also giving away a $250 gift certificate to the best testimonial about the store. For more info, go here.