I used to be in a Play by Mail league when I was at school - I thought Championship Manager had killed these things off completely. The one I was in was run by some guy in Nottingham on his Atari ST.
For a PBEM league to be worth paying for, it would have to be spectacularly good - CM has us all spoiled.
I agree CM and more recently FM are tremendous games and I play FM for hours on end but PBEM offers something completely different in that manager interaction makes the game highly enjoyable. That for me makes PBEM games stand out and I'm having a great time at the moment trying to persuade some Premiership managers to sell me their players. This one in particular imo is amazing with great value for the 50p, and its free to recieve the first turn.
In other news I got my first turn of the season today and lost 2-0 away to newly promoted Millwall, whilst drawing my second fixture 0-0 with Sheff Wed. Not happy.