Hi, new to your podcast and understand that you are looking for topics the podcast. May I suggest the following
– Linux desktop
– first KDE deskotp
– concerned with KDE’s dependence on the (then) non-GPL Qt widget toolkit , GNOME desktop was born
– ironically years laters, the group/person who started Gnome started another project Mono, which falls into “similar concern” that most opensource people feels
– Ubuntu, new Linux user’s love affair
– didn’t contribute much technical but did managed to great PR for themselves, helping Linux as a by product.
– free, open, technically good if not better
– great minds working towards same goal of freedom
– contradicting each other along the way, e.g. KDE/Gnome, Gnome3/Unity,
– GIMP, one of the most recognize app in Linux, is maintained by only a few (i heard somewhere only one) developer
– to get sound working, you’ve get alsa/pulse-audio/jack/etc so that you can crash your system
– everybody cannot agree with anybody
If you happen to look into the above few topics, you will have tons of research to do but the outcome will definitely interest many many more.