http://en.wikipedia.org/wiki/List_of_companion_plants

This one doesn't list any plant at all that has a negative effect for spearmint. Spearmint is a weed almost. I've been told by many people not to plant it at all, but I like it and plan to grow it anyways.

What's the thinking behind this idea? I would have thought the mint would deprive the pepper of space, water and nutrients. Anyway mint is perennial while peppers are generally grown as annuals. I'd give the peppers their own pots and put the mint somewhere else.

I agree with flora_uk. Separate pots. Unless all you want is one season of sort of 'pretty'. If you want any yield from the peppers or the mint, let them grow apart from each other. Especially true if you don't even know what variety of pepper you are dealing with.

Mints are conisdered weeds because the spread so rapidly. Containers with mints works best. Peppers with any mint should do well because the mint will shade the ground and create humitiy. planting any of the nightshades(peppers, tomatoes, eggplant ...) with a ground cover is a good idea.