The primary use I can think is that for someone who likes to give Perl talks and wants to give a talk (about anything), they may consult this list to find something that strikes their fancy.
Another user could be someone who would give a talk if they knew that something about which they felt comfortable talking was of interest to other people, they may step up.
The immediate problem being solved here is a local one - at Houston.pm we're constantly asking the mailing list for topics or speakers to volunteer. Even though it is a local topics bank (act locally, right?), I'd like to get ideas from anyone willing to contribute.
Eventually, I'd like to make this a list that is appropriate for any event or meeting where people talk about Perl and the interesting things we're doing with it.
If you're uncomfortable with forking, editing, and issuing a pull request; please just create an issue with the topics you'd like to add.
Hope to see you contribute to the topics list.