Good list. I will caution everyone, before they go hogwild on a list of PPC services, to master one before moving on to the others. Adwords is where 80 - 90% of your business is going to come from (unless you are in some bizarrely unique niche). Spend some time in the Adwords learning center or hire a company that can do this for you.
Also check out Andrew Goodman's book, Winning Results with Google Adwords. Make sure you get the latest edition.
Once you have Adwords down, then move on to capturing the rest. Good luck!