What does it mean when a dot appears in a logic gate other than the NOT gate? (in logic diagrams) For example, this gate: 

looks like an OR gate, except there's a dot to the right. The dot is reminiscent of the fact that there's a dot in the NOT gate, so I wonder if it has something to do with that. There's no NOT after this gate in the diagram I'm looking at, so this doesn't to be implementing NOT OR or something like that...
This is a NOR gate. You can implement a NOR gate using a combination of a OR and a NOT gate. However, in MOSFET implementation or other technologies (i.e. electrical hardware architecture), we can build a NOR gate directly and more efficiently (i.e. more efficient than using a OR and a NOT gate). That's why we use NOR as well.