Well, everybody keeps saying that Google Adwords is the end-all be-all, but I have had no luck with it. I have blown through hundreds with not a single sale from Google.
I HAVE had luck (albeit only a little of it) with the HostQuote leads from Webhosting Talk. I have gotten 3 resellers and 3 regular hosting customers this month from them. Those customers alone have more than paid for the membership. Of course, I don't bother with 90% of the leads there because they want the world for $1.
I have gotten a couple of customers from various forums.
I have tried the Hosting Directories and they are a huge waste of time.
I am going to try something new. I purchased a bunch of postcards with a scratchoff that reveals a "30 Days Free" under it. I will be doing a local mailing with these scratch-offs. I am also looking into having an insert placed in the local newspaper advertising a promotion available only to local residents. I have a feeling local advertising will be the way to go.