Game Fluff
The gestalt idea of this game is "The story of King Arthur retold in Eberron".
Essentially, one of the players will be an expy of King Arthur - the last royal prince(ss) of Cyre, raised in anonymity. This game is set a little farther on down the line than most Eberron games, being about ten-fifteen years after the Last War's end (exact date to be hammered out by consensus among the players). Our little lost monarch was smuggled out of Cyre just hours before the Mourning, raised unaware of their birthright, and now the players must not only discover the royal's heritage but also prove it - and just maybe re-establish Cyre as a nation. (Prince Oargev ir'Wynarn is not properly a prince, being merely adopted into the royal family from a cousin.) The shape of it is largely up to the players, and it is very much an RP-heavy, player-driven story.
Game Crunch
The game itself is D&D 3.5E, and while I'm pretty open to most any source material and homebrew I do ask that you run anything non-core by me, first. I am passably familiar with psionics, incarnum, and most other variant rules, and have just about every splatbook published by WotC, all of the Dragon magazines, and Dragon Compendium. I am much kinder to level-adjustment and monster characters than WotC was, and am very amiable to working something out when it comes to a monster character. The house rules in effect are Weapon Group Feats, Armor-as-DR Class Defense Bonus, Spell Points (and I have the calculator to work out things like the Duskblade, too, in case you wanted to play one of the non-standard casters), and Vitality and Wound Points.
Character Creation
Characters begin play at third level, with all of the rolled gold (including that gained from backgrounds, below), plus 2,600 gp. They may be of a LA +1 race (with the Level Adjustment bought off) or may begin play with a Background (see below). While permitted magic items to start off with, they cannot be more than three-quarters of your total worth (about 2,000 gp, give or take depending on how the rolls go). Stats are generated from 4d6, dropping the low, selecting the best from the three sets. Alternatively, 36 point-buy. Vitality points are maximum for the first three levels, but afterwards are rolled (with one re-roll - and you must take it even if it's worse).
Setting Changes
Ordinary D&D drow exist in Khyber, along with most of the rest of the Underdark stuff. They just don't have much interaction with the surface, much preferring to keep to themselves. True to Eberron form, their alignments run the gamut but still tend towards evil. It's more the selfish and amoral evil than the "BWAHAHAHAHAHAA" evil most drow societies exemplify. Lolth is a renegade ('almost sane') Daelkyr who spends as much time fighting the other Daelkyr as she does anything else.
All Khyber drow who have dragonmarks have aberrant dragonmarks, and almost all of those are Marks of Xoriat (Dragonmarked p 143).
Valenar are wood elves, while Aereni are grey elves. Khorvaire elves are high elves. They can all take true dragonmarks, an exception to the rule about subraces, but the Mark of Shadow is rare among the Aerani and even more so among the Valenar.
(I'm also thinking on how to incorporate Ghostwalk into Eberron, perhaps with the Mournlands as a manifest zone and the elven spirit trees in Aerenal. Ideas?)
House Cannith has a new type of magic weapon in the elite markets of the Five Nations, drawing from stolen drow designs and Xen'drik thaumaturgy. Cannith designed these magelocks in the last months of the Last War, selling them to Cyre; the only surviving examples were in Sebastian d'Cannith's company, left behind to fight a rearguard action while the rest of the army retreated. They are techno-magical devices powered by a Khyber shard bound with an elemental mote, still quite rare but rapidly gaining in popularity with the wealthy - particularly adventurers. The gnomes of Zilargo have their own, essentially identical, versions that they unveiled in 997, three years after the first Cannith designs emerged in Cyre. Rumors persist that other magelocks utilizing other elements - such as ice or electricity - are either in development or exist already, but thus far only those utilizing fire are common on the surface. Magelocks are available for purchase in House Cannith South and in Zilargo. Thrane has banned them, and Karrnath is considering it. They are very rare weapons, each a unique work of art.
The addition of these magical weapons lends towards a more swashbuckling feel to the game, one which contrasts and complements the Arthurian elements while emphasizing the steampunkesque elements inherent to the Eberron setting.