Help with email list monetization.

In my professional life, I'm a programmer. I do a lot of web scraping and data mining jobs that involve getting leads for clients. Along the way, I've started to keep a database of thousands of email addresses categorized by search terms (in order to keep the lists targeted). How do I begin to monetize these lists? I'd really love to stop working for other people, ya know?

1. Delete this list from here as soon as you can... because now people gonna spam them and you will decrease your chances... Better: 1. Sell targeted lists or 2. Better use them to earn from their category.... Btw which categories-niches do you have lists of?