Oftentimes I will read Hub (questions) or view some of the hubs on the newsfeed. If you feel strongly one way or the other about a subject matter it can lead to writing an insightful hub on that subject.
The bulk of my hubs are on dating and relationships. There is no shortage of inspiration under the topic of "gender relations" in my opinion.
I try not to put any pressure on myself to write just to be writing. My best writing comes from having a strong opinion about something that I've read or heard about.