Here's your ultimate (chronological) guide to Thor reading:

 

MIGHTY THOR OMNIBUS VOL 01 HC
THOR FIRST THUNDER TP
THOR IF ASGARD SHOULD PERISH PREMIERE HC
THOR THE QUEST FOR ODIN PREMIERE HC
THOR RAGNAROK TP
THOR THE ETERNALS SAGA VOL 01 TP
THOR THE ETERNALS SAGA VOL 02 TP
THOR BY WALTER SIMONSON OMNIBUS HC
THOR VS SETH THE SERPENT GOD TP
THOR BLACK GALAXY SAGA TP (due 7/20/11)
THOR BLOOD AND THUNDER TP
THOR WORLDENGINE PREMIERE HC
THOR LOST GODS TP
THOR BY JURGENS AND ROMITA JR VOL 01 TP
THOR BY JURGENS AND ROMITA JR VOL 02 TP
THOR BY JURGENS AND ROMITA JR VOL 03 TP
THOR BY JURGENS AND ROMITA JR VOL 04 TP
THOR ACROSS ALL WORLDS TP
THOR THE DEATH OF ODIN TP
THOR LORD OF ASGARD TP
THOR GODS ON EARTH TP
THOR SPIRAL TP (due 7/13/11)
AVENGERS DISASSEMBLED IRON MAN THOR CAPTAIN AMERICA HC
THOR BY JMS OMNIBUS HC
**THOR BY JMS VOL 01 PREMIERE HC/TP
**THOR BY JMS VOL 02 PREMIERE HC/TP
SECRET INVASION THOR TP
**THOR BY JMS VOL 03 PREMIERE HC/TP
THOR LATVERIAN PROMETHEUS TP
SIEGE PREMIERE HC/TP
THOR SIEGE PREMIERE HC/TP
THOR SIEGE AFTERMATH TP
THOR THE WORLD EATERS PREMIERE HC

**THOR BY JMS PREMIERE HC/TP ARE CONTAINED IN THE THOR BY JMS OMNIBUS HC