Pythia Oracle
Pythia Oracle (github link) is an open source, desktop-based, cross-platform application designed to serve as an "all in one" solution for solo gaming, and to facilitate random content generation at the table.
It's basically a mashup of a text editor, dice roller, and a ton of random tables. Plus solo oracles (like Mythic) and mapping and character sheets and a triggers system to give you that old time "real GM" feel, haha.
And it uses templates to output blog, web, and pandoc friendly files automatically, whenever your log is saved. These templates are customizable and extensible, and, like saved games and pretty much every other part of Pythia, plain text.
The help document has a comprehensive overview and detailed examples for each feature and button.
And here's a link to the main project page but it's a little out of date and doesn't list all the newest features. See the changelog for those.
Pythia is currently holding steady around 1.4.0, since I can't think of anything else to add or tweak. Feel free to report bugs, make feature requests, or discuss any issues on the github repository!