This is a totally unofficial list that I put together myself over on the Glorantha G+ group. So details may be wrong but a lot of this has been officially confirmed (e.g. that the product is planned, though not when it will be released).
I thought I'd share it here, for fun and info.
Upcoming new stuff, officially confirmed
13th Age Glorantha rulebook - Rob Heinsoo, Jonathan Tweet, Ash Law and Jeff Richard - PDF available now
Glorantha Sourcebook (via 13th Age Kickstarter, but not system-specific) - Jeff Richard - PDF available now
The Gods' War board game (Kickstarter, release in 2018) - Sandy Petersen
RuneQuest: Roleplaying in Glorantha (RQG) - new Chaosium version, based on RQ2
RuneQuest core rulebook
RuneQuest Bestiary - a hundred or so entities and a few short cult write-ups
RuneQuest Gamemaster's Pack (including screen) - including the Colymar tribe setting, three scenarios and player aids
RuneQuest Cults book (aka The Gods of Glorantha) - around fifty long cult write-ups
RuneQuest scenarios book – a collection of brand-new scenarios
Glorantha Quickstart booklet - 48-page booklet, free PDF
RuneQuest GM's Book
RuneQuest Dragon Pass Campaign
Gods of Chaos
HeroQuest publications
Non-Gloranthan HQ genre packs - Ian Cooper
The 'rebel' story from Sartar Rising (i.e. Battle of Iceland, Dragonrise) that you can weave as additional events into your 'clan' campaign - Ian Cooper
Fonrit book - Ian Cooper
Other Glorantha publications - rule system TBD
Nochet guidebook - Harald Smith
Casino Town/Holy Country book
Trollpack vol 1 ("troll info and adventures for humans") - Dan McCluskey
Trollpack vol 2 ("everything you need to run troll PCs in a trollish setting with a campaign based around trollish clan life") - Dan McCluskey
Trollpack vol 3 ("covering Dagori Inkarth with a full description of Redstone, and takes the campaign literally from 'tussle over a cave' into creative heroquesting, PC heroes stomping around like a chit in the DP wargame, and climaxes with one of the defining magical events of the Hero Wars") - Dan McCluskey
Dragon Pass - remodelled version of the classic board game, via Kickstarter - Chris Klug
Riders of the Storm: Nomads of the Wastelands (Praxpak) - David Scott
Six Ages (computer/mobile game, the successor to King of Dragon Pass) - David Dunham
Gloranthan Adventures 3 - Defending the Dark (from D101) - Newt Newport
More speculative
Greg's own Harmast's Saga
Disappeared from the radar/MIA?
Glorantha Bestiary - Pete Nash