I've been collecting undead skeletons for my army and I've been looking around for skirmish/rank&file games with undead specific rules and I've found some good ones I'll be using the rules for sooner or later; But I'm looking for some other suggestions since other folks might've come across some games I've never heard of!

Here's my list:
Dragon Rampant
Oathmark
Frostgrave
Onepagerules Age of Fantasy
Saga age of magic
9th Age
Kings of War
Conquest: Last arguement of kings (Proxying for Old Dominion)
Relic Blade

Miniature-Agnostic/Scale/Theme doesn't matter, I'll only ever be playing friendly games and I'll nab some scifi-undead/magnets if the game looks neat.

If the game's solid and doesn't have specific faction rules go ahead and mention it, like Frostgrave for example.

Also, if you know any community rules based on GW/other established IP's go ahead and mention them, The stuff from Servo_Skull I think is solid.

Grenadier's Fantasy Warriors had rules for the undead in a supplement.

Rick Priestly's Warlord's of Erewhon has an undead list.  His blog, This Gaming Life has lots of fun lists including totally non-proprietary chaos rat men men things and doped up goblins with balls and chains.  We played it a few times, the game is fun but the exchange of missiles rule needs some toning down.  Personally, the army lists are great, the rules are okay, the order dice activation is okay but never quite feels right for a fantasy game.  They needed to do something more with Ambush orders.

Martin Hackett's Fantasy Wargaming book has a set of rules with written orders and undead stuff.  See if you can find the second edition.