Back when you could create accounts with usernames instead of emails, I wrote a c# program that would generate a random user/password/DOB, go through the three web forms, and create an account. I integrated this with TOR so that on every third account, I'd switch IPs to prevent throttling. I'd let the thing run almost constantly and ended up with thousands of accounts.

I sold these account lists to botters who would then go on to to their thing. Made a decent amount of money from this too!