Issaries also produced Oliver Dickinson's Collected Griselda - Third Age stuff in Pavis and the Big Rubble (unlike the glory that is second age Pavis) but definitely Runequest fiction rather than Heroquest :wink: Many of the stories first appeared in White Dwarf back in the day...
tradetalk.de is the site to check for the Penelope Love book (which I loved) and the Paths of the Damned (a Glorathan comic book). They also sell back issues of Tradetalk and Tales of the Reaching Moon - professional-quality Gloranthan "fanzines" - both of which contain the occasional piece of fiction. Again Third Age.
And for the hardcore you could try and pick up Greg Stafford's King of Sartar on ebay or the like, which tells you exactly what happens in the Hero Wars at the end of the Third Age - from the point of view of the victor's descendants, so it's obviously all true!
Ye Book of Tentacles (also available from tradetalk.de) has some fiction in them - YBoT 3, I think, has a whole load of pieces from a Gloranthan short story colection that never saw the light of day.
Online mything links is a great place to start from as is lokarnos.com. Some of my favourite pieces (all good Orlanthi stuff) are by John Hughes and can be found on his Questlines site
http://mythologic.info/questlines/questlines.html
I'm still reading the Companion, Runes of Chaos and Ralios pdf but if I get a chance later I'll check my books for any more recomendations (and decide whether I want to put my spare copy of KoS on ebay now that the RuneQuest renaissance is on us. Again...)