Fudge used to be FUDGE, but these days it's just plain Fudge.
The author's pages are probably the best centralized place for information about the system.
Below are the rules I've written for Fudge over the years. Feel free to use or modify them according to the license contained inside-- which boils down to you can use them for free, but you can't redistribute them in any form without my say so. This is really only so I can get you to send me free copies should you use them in a published game or volume. I can usually be contacted at the address below.
Combat Options is a set of independant rules modules. Most of this was abstracted from Compleat Combat, below. The difference is that these rules are designed to work together or with any other set of Fudge rules, including the basic combat system in the core Fudge rules. Included are rules for Armor, Shields, an alternative wound track, and a new damage system that I think of as my crowning achievement.
Compleat Combat is a complete combat system, incorporating weapon definitions, armor, combat, damage, and recovery. These rules are really designed to be used as a whole, and are slightly different from the versions you read in Combat Options, above. This started as a conversion of BTRC's Guns! Guns! Guns! weapon creation system into Fudge. Compleat Combat can be used for any setting, from archaic to fantasy to science fiction, and includes both melee and ranged weapons into the same mechanic.
Experience and Character Development covers character advancement. There are a multitude of different experience systems out there. I like this one. But then, I'm biased. The basic thrust of these rules was to create a non-deterministic advancement system, which would encourage players to add a bit of role-playing to the usual between-session skill advancement.
Wealth describes a character's wealth in Fudge terms, using a Fudge attribute. Doing so allows the buying and selling of things to be handled as a normal Fudge action resolution. This can free players from having to track their cash on hand, which I've always found to be a tedious bookkeeping function.