there's leaf armor from dragon magazine ... it's 3.0 and from what i read there were a few designers (SKR for one) who didn't like it all that much (not hate, just didn't like it)
Leaf Armor: presented in Dragon 279
• Only non-metallic armors are affected (padded, leather, leather scale, hide, dhenuka)
• -5% Arcane Spell Failure
• +1 Max Dex
• -2 Armor Check Penalty (includes MW)
• +750gp Market Price
doh! sorry nothing for making it light armor ...
Have you used the Black Company CS MW rules at all? They have a completely expanded MW system that you could use ... and is open to other MW type benefits. Here's one idea
• Mobile (armor):
This armor is less restrictive and easier to run in, it counts as one category less for movement and special abilities
Benefit: Medium armor counts as light armor for movement/SA. Not for proficiency.
Double: Heavy armor counts as medium armor for movement/SA. Not for proficiency.
Triple: Medium or Heavy armor counts as one category less (light/medium) for movement, Special Abilities and proficiency.
[edit] ... the way MW works is depending on the quality of the items you get to choose the amount of bonuses you want. Standard 3.5 equipment is accurate (for weapons) or mastercraft (for armor). You can go ahead and get different benefits ... ie you could get a balanced shortsword (+1 init) instead of an accurate shortsword (+1 attack).
ask your DM if instead of a typical MW hide armor (-1 acp) you can get one that is considered light armor