These are the house rules we'll be using for the campaign. Like you might expect these are subject to change over the course of the campaign; if you have feedback, feel free to send it my way.
Characters should be made at 3rd level, 28-point buy, hitpoints max possible at 1st level and 75% of max (rounded down) every level after that*. You have 2700 gp to buy equipment, with no single item costing more than half that. Please note how your character obtained any permanent (non potion/scroll/wand) item.
*For you people with 1d6 and 1d10 hp/level, you can if you want calculate 75% of the total rounded down, rather than 75% of each level rounded down -- so someone with 1d6 hp/level who's 3rd level would have 6 + floor(.75*(6+6)) = 15 hp rather than 6 + floor(.75*6) + floor(.75*6) = 14 hp.
You can choose from any of the standard classes, plus the new Eberron class of the Artificer. If you can find a class elsewhere that seems setting-appropriate, I'm open to discussion. For instance, Dungeonscape introduces the Indiana-Jones-esque Factotum which seems like it'd fit in fine. Prestige classes won't be available at the start (as you'll be too low-level) but I encourage you to think about taking one later, since what the hell.
The goal here is to be able to call for skill checks more often, in a wider variety of circumstances. The solution is two-fold: give people a broader range of skills, and make less skill checks be "make this roll or the adventure breaks (or brakes)".
As part of fixing the first problem, all classes get 2 more skill points per level (and 4x that at first level, like usual). Profession and Craft are considered in-class skills for all classes. The feats that give a +2 bonus to two skills (Acrobatic, Deceitful, etc) also make those skills class skills, as does getting a bonus to the skill from your race. Additionally, the following skills are combined (classes that have any of a set on their class list have the new skill on their class list; the bonus from class/race/feat/synergy is the highest bonus given for any in the set, not the total).
So much for the first problem. The second problem, then, is that there are too many skills that are either primarily useful in situations where the check has to be made or the adventure can't continue (Gather Information); or they're primarily useful in situations where the whole group has to make the roll or it's no help (Move Silently).
The solution for problem 2a is that the characters get the information regardless, but they get rollover bonuses for succeeding on the check. I'm not quite sure about the numbers here, but right now I'm thinking it's a basic DC 10 check to get a +1 bonus, and for each 5 by which the DC is passed (15, 20, ...) the bonus is increased by +1. This can be applied to up to three rolls relevant to the skill check: Intimidate can give attackers a penalty to hit you, Gather Information can help bypass exterior defenses, and Knowledge (religion) can give a bonus to the saving throw against a ghoul's paralysis attack. If the check is failed (they don't make the DC 10), the characters still get the information, but there might be some other consequences of their action (word of their information-gathering attempts get back to the guy they're trying to find out about, or the person is intimidated but secretly vows to take revenge for the humiliation).
The solution for 2b is to have only one person roll for the group whenever possible. Per some rule I saw on rpg.net, this is the person with the highest skill when the group can take their time, and the person with the lowest skill (so probably a person with no ranks in it) when they can't. Possibly in the latter case the highest-skill person can make an Aid Another check to assist. This rule applies only for situations where either the whole group benefits or they don't: likely situations include Climb checks to scale a wall, or Diplomacy checks to impress the Duke. Situations where characters can succeed or fail individually, like making Balance checks to keep their footing on a slippery floor, still get rolled by everyone individually.
Instead of the usual feat at 1st, 3rd, 6th, and 9th level, characters will be receiving a feat at every level. The intent of these additional feats is to give the characters a little more breadth and people are encouraged to use them for stuff more like Alertness than Power Attack, but feel free to use them for whatever you think best. Remember the rule mentioned above that the feats that give a +2 bonus to two skills (Acrobatic, Deceitful, etc) also make those skills class skills, and check out the variant rules section at the end for some other modifications to feats. There are a large number of Eberron-specific feats you might be interested in, which I'll try to get together a list of at some point.
Action Points are a new thing introduced in Eberron (or, technically, d20 Modern, but never mind) similar to Drama Dice or Hero Points or whatever in other systems. By the standard rules, you can spend an Action Point to:
I'd like characters to level up every 2-3 sessions, and I don't want a lot of bookkeeping, but I want to reward people for attendance. Therefore I'll be using a simple alternate system: at the end of every session you gain half a level. At the end of an adventure if you're lower level than the average party level you gain another half level. In between adventures you can level up, assuming you have enough xp.
This system obviously doesn't account for other places in the system where experience points are spent: certain spells and when creating magic items. Therefore we'll be trying this craft points systems, with two modifications: xp costs for item creation are dropped entirely, and you can also spend craft points on casting spells that require xp (at 1-for-1 conversion). If the pool isn't sufficient, I would be happy to arrange adventures to retrieve craft-point pool equivalents: rare ingredients, construction on ley lines, that kind of thing. If someone decides to play an Artificer, I think the most reasonable way to handle it is to give them 50% more craft points per level, and their xp-salvage ability becomes a craft-point-salvage ability.
There are a couple other variant rules I'm thinking of tossing in. My gut feel is that this campaign isn't likely to be extensive enough for real cracks in the system to show up, so it's probably not worth adding a bunch more rules to remember. On the other hand, a few changes might improve things, and besides, I have an incorrigible urge to tinker. But yeah, this is all still "for consideration", not "official".