In many respects, the Explorer's Handbook is a DM tool than a player one, though that isn't a bad thing. Lots of good fluff. I especially like "How to Survive a Human Sacrifice" sidebar.
Crunch:
Chapter 1: Prices on travel, especially long range.
Chapter 2: Elemental vessel properties (how to control, consequences of attacks, etc.)
Magic Item: Life rings (feather falling life preservers, last 8 rounds)
Misc: Discussed traveler's marks (signs that warn of danger, food ahead, etc. Survival based)
Affiliations: Wafinder's Guild and the 12's Acquisition Directorate. Not flushed out as PHBII style (so, its soft crunchy---"squishy?)
PrCs:
Cataclysm Mage: Mage that studies Eberron apocalypses. 10 level, all but one +1 CL. d4 HD. 6th to start, need an RP vision or visitation. Gain various abilities tied to different periods of history, but must continue to seek out visions to keep power. Abilities (in rough order of acquisition): while fulfilling vision, use d8 for AP [first 4 only], create magic items with some components for free (keen, mighty cleaving, bane, thundering, viccious or arrow catching, bashing, ...) [only XP affected, gp as normal]; immunity to insanity; open a gateway to Xioriat briefly, causing pain, slow movement, and cannot hold items; maximize repair spells once for free per day; +2 saves vs. psi; cause a quake like effect 1/day w/in 20' with fear in addition; +1 save vs enchantment; +2 to overcome fiendish spell resistence; create a flood of silver fire that does 1d6+class level per round no save for class level rounds max; ability to chose to manifest any non-Syberius dragonmark (but only one a day) with the possibility of dragons hunting you down.
Thunder Guide: Storied explorer. +4 BaB with some diplomacy, must have visisted several non-Khovair places. Mid BaB, good Fortr, d10 HD. Gain languages over time, and various spell-like, supernatural, or extraordinary abilities over time; ties to native cultures; famous in the press; catch people while falling w/ Climb, grab people on horses w/ ride; money from fame; lordship from fame. Lots of small abilities similar in vein as horizon walker benefits but w/ Eberron flavor.
Windwright captain (one I'd love to go to): Airship or elemental galleon captain. Have to be half-elf w/ dragonmark, usually rogue/sorcerer, rogue/wizard, bard, or artificer, at least level 8. 5 level PrC, d6, +3 CL. Assists in controlling elemental and vessel, gain access to a ship (access, not ownership, though you can buy it if you get really wealthy later).
Infusion: Invoke Elemental. Free a bound elemental briefly to fight for you.
Chapters 3-5: Fluff
Appendix: Magic Items