For instance, it occurred to me that the question "what's the difference between using 'sudo su - username' with and without a hyphen?" might be useful to others to have an answer to. Is it okay to ask it myself and then answer it myself, so as to include the answer to that (or any other) question on these sites. (I assume that one would be for superuser.)
It's possible that this question might already be answered on superuser.com, but that's not the point. Substitute any example question you want: is it okay to answer your own questions, and even to ask them with the purpose of answering them.
The only reason not to do this, that I can see, are that some might perceive it as "gaming the system" to get more points. But the reason for it is that it improves the supply of (hopefully) good questions and answers. And I think the points would still be fairly earned.