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Whales $50K - Higher/mo
Big Fish: $10k -50k/mo
Medium Fish: $5k-10/mo
Little Fish: $1k-5k/mo
Pond Algae: $1-100/mo
Not to offend anyone with the Pond Algae. If you fall in that category, then you're in the right place to learn. We all started there and it's a fun swim up. :)
As for keywords/programs. Keep playing with the Overture suggestion and bid tool. There's a simple comparison tool at Search Engine Garage. But really it's just finding some niche and good content.
I could tell there were some whales at the pub conference... if you've never been, you owe it to yourselves to check one out.
However, this is unlikely to be a guy working from his backroom. High traffic sites such as MSN etc. still run aff programs, and it's generally this type of operation that makes the big bucks.
There are also loads of scumware affs, such as Gator, WhenU, 180 solutions, etc. who do fantastically well at someone else's expense.
Get a good (as opposed to cheap) accountant and you'll get their costs back several fold. Ask someone real rich that you know to recommend one, as opposed to using the Yellow Pages or similar random method. That's what I did anyway.