Train them 3-4 times hard in your routine, i use to only train them like...maybe once a week if that... doing that kept them small, way underporportioned..but bumping it up i saw it increase of about 2 and 1/2" over 3 months, although, as someone posted in another thread, i just tried this yesterday, my leg day --->
http://webcast.bodybuilding.com/fit...30/week30wm.htm
and it is pretty wicked... never had my calves this sore, and only after that one workout it seems they grew!?
i did 4 sets..
I use to own a pair of weak forearms too, have seen a great increase in my forearms for size--my routine looks like this:

unish them;GO HEAVY
2 warm ups--
-Reverse BB curl ~4x15
---SS with---
-Seated BB wrist curl ~4x12-15 (i use a benchbb and 30lbs)
-Alternate Hammer ~3x15 (i try for four)
-Seated Reverse BB curl ~3x15
and if your gym has the rope thing--um? a plate on a string to a bar? use that too....
whats that called?