Interestingly enough, I find you can either get spammy and low-quality and cash out a lot now, or build a legitimate audience and following, and create revenue that lasts for a long time. The spammier you are, the faster you make money, but the faster it disappears.

There are four obvious ways you can make money from this:

1. Find a good affiliate program, hawk their goods every now and then, and make a small percentage. This is surprisingly hard, but when done right makes a bunch.

2. Drive traffic to a site with adsense. You have to drive more traffic than you would ever believe, but it's relatively secure.

3. Sell tweets/promotion to other folks. This is pretty easy, but obviously you won't have much control over what people are using your accounts for.

4. Create/license what blackhatters call a "panel," and write an automated way anyone can come and use your accounts for a fee. This usually requires a lot of really small accounts, not a few big ones, but even blackhat noobs can make $100/day with a couple thousand accounts doing this (you can buy accounts for cheap). This gives you even less control, and basically turns you into a giant spam bot.

Contact me off-list and I can explain a little bit more in depth how it's done and put you in contact with some good folks (email in bio).

Be sure to check out sites like instafluence.com and sponsoredtweets.com (even celebrities). Legit companies pay a lot of money for promotion from big accounts. I know candycrush was paying over $1/download, and a few people pulled in $10K+/month. There are even people making a few thousand dollars a month selling cheap tweets/posts to places like fiverr.com or seoclerks.com - generally lower quality, higher volume accounts. It sounds like you've figured out how to grow them though, and if you can scale that out you've got a money making machine.