I use the following tools to play my solo rpg sessions:
The Mythic Game Master Emulator: I don’t use the full package, just the Event Focus, Action and Subject charts as a random idea generator to create scenes, events and encounters.
The 9Qs Solo RPG Engine: You can get it at the Solo Nexus blog and it provides an alternative way to the Mythic Emulator to create a structured gameplay for a solo session.
Rory’s Story Cubes: I have the Voyages set. Whenever I need inspiration and I don’t want to bother with a table or chart, I just draw two story cubes randomly from a bag an roll them.
Custom random tables created for the specific genre I am playing: Some simple tables where I roll one die for every collum and combine the results. For example in a D&D game I have a table with the collumns Race, Class, Appearance, Quirk so for example I might generate a dwarf cleric who is missing an eye and constantly cracks his knuckles.
Several random dungeon generation tables for the classic story-light miniature based dungeon crawl.
I might use some other tools every once in a while but this is the basic arsenal.