PDC is PayDotCom. I use PDC and Clickbank. I occasionally promote other products through their own affiliate network such as The Second Tier.
Generally just clickbank cause they're reliable and you always get paid although I do have a CJ account.
^^ Commission Junction The network doesn't really matter, there's nothing magical about CB, the only difference is that there's only digital stuff... that'd be more like a limitation instead lol, because you'd never be able to promote stuff that are physical objects... diversify people... you can't target ALL markets from CB you know... Personally I'm with CB, myHelpHub, PDC and Market Leverage and like Elward a few smaller ones, for example The Second Tier.
Just Clickbank right now until I get to an income level with them I'm happy with. I have a Copeac account but haven't done anything with it as of yet. That's a whole other sandpit to try and play in.
Having any luck? I am using mainly the computer and electronic merchants without much luck thus far...