Before you start considering your eBook topic you should get a notepad and a pen in front of you. Every time you find a new topic just write it down. No topic is too stupid to be written on the list. Just note it down and leave the considerations of the topics for later.

The first you need to look at is your own interests. The odds are good that there are thousands of other internet searchers that have the same interest and are interested in information about the subject.