We also call the V , "uve" or "V chica" . Apparently 'uve' is the new official form to call it (see link). I've been calling it 'uve' since I can remember, but when i was a kid, it was very normal (in my region) to call it "v chica" or "ve de vaca" haha.
Another clarification , besides the ones that Rich has given (vaca and burro) is calling it 'B labial" (lip B), i guess it is because we use the lips when pronouncing it and also 'labio' is written with it.
By the way, the link also talks about the removal of CH and LL as letters...yes!!! Some genius figure out that these should be treated as new letters in some point of history, but (thank God) it didnt last, because the number of letters in the spanish alpabeth changed during that time, and it was a bit confusing when I was a kid...Also the Y is now officially "ye" but before it was "I griega" or greek I, and the I was "i latina" so that we can difference between Y and I (when alone, because we all now what happens with Y gets allong with a vocal). So now is just I and Ye :)