Some of my favorite Bicep exercises are 21's
They will work multiple parts of your arms at once, and they are wicked effective..
I also like pyramids.. I would suggest doing both of them. I just got back into the gym this week after 3 months because Ive been so busy with work, and I lost 60-80lbs on my chest excersises.. I didnt lose ANY on my arms.. the pyramids and 21's have a lot to do with that I think.. Also Maybe i missed it But are you doing preacher curls? one of the guys at my gym suggested I do preacher curls with the 45lbs straight bar and like a 25 on each side.. It doesnt seem like a lot but it will kill you.. They are a lot of fun.