All those people with funny names are spammers. They try to post their links here for many reasons. Most are pretty harmless, but some links can give your computer a bad bug.
Never click on a link posted by people with funny names.
I try to ban them as soon as I can, but some slip through now and then. banning the user will block that persons IP and email address. Blocking the IP and email address prevents the same spammer from registering again. If I delete the account, it makes it possible for the same IP and email address to register over and over.
This is just one of the issues I deal with a regular basis here. There are a lot of preventative measures in place and out of about 100 attempted registrations per day, only 3 -4 actually get through.
If you look at the membership of some smaller sites, you'll see membership in the 10's of thousands, but only 10,000 posts. These members are almost all spammers.