So not females together, but they can be ok with other species of fish potentially? Females CAN be kept together but like I said need to be provided with plenty of hiding spots and should be kept in a heavily planted tank.
I believe that you cannot put a male with other types of fish, correct?
Yes you can, if your male is docile (which isn't always the case) and plays nice with others. You also need to be sure that the fish he will be residing with don't have long flowy fins (because a male betta might see this as a threat) and they aren't fin nippers because we don't want any shredding fins going on. I really wouldn't attempt this unless you know what you are doing.
What about having 2 near each other? I saw a little beta tank in the store that was a rectangle with a glass divider in the middle.
Betta's need to be provided with a minimal of 2-3gallons per fish the more the better. Those small bowls are inhumane and don't give the these fish the quality of life that they deserve. You can however purchase a 10g tank and fit a divider in the middle and safely and humanely keep one betta on either side.
I have heard of males hurting or killing themselves trying to get at each other when their bowls are too close. Would the same thing apply to say a male/female or female/female pair kept close (but separate) like that? If you are going to attempt this then you need to make sure there is no possible way they can get through to each other or jump over.
I am toying with the idea of putting a beta in the tank with my dojo, but I am also toying with the idea of putting a beta bowl in my iguana's cage (where it will be safe from being knocked over or pooped on of course) as they love watching colorful things move. lol If I do that it would be fun to have at least 2 but would do little good if the fish killed themselves. lol