What law/legal related businesses can I open with a law degree?

A lot. Some you do not need a law degree for, but having one just makes it more credible. Here are two easy ones... You could start a legal courier business. Law firms use legal runners, usually college kids making $10 - $17 per hour to run errands. These errands can vary from parking cars and making coffee, to filing paper work at courthouses and delivering materials. In areas with several hundred law firms, these services are helpful and having a law degree would make other attorney's feel more comfortable. Also, you could start a process service company (serving subpoena’s). Often lawyers do not want police serving these, because of the vibe they give, people can see them coming from a mile away and duck them, and they do not tend to make it a priority. Once again, having a law degree makes you knowledgeable in this area or at least perceived as knowledgeable, lol...

A law office. Hire some lawyers and make a team of "The Best".