Hi Tamerlaine. Welcome. I'm running two PbP games here, one of which can't accommodate new players well, but the other,
Enter the World of Greyhawk, could allow for a new player. Lord knows there have been a few. There are some house rules that you would need to read up on and, if you're still interested, contact me and we will see from there. You could take over a man-at-arms or perhaps we'd kill him off and we would introduce a new character, altogether (we'd enter a new character, altogether).
And, as Tumblingdice mentioned, there are a number of games at the
Unseen Servant forums also (and they have a nifty dice roller). I play in two at the moment and have played in others there. Good group of folks.