Now, I don't have all of the books that have been published, so I might be missing one in which a skill like this is described. Essentially, I'm looking to pick up a Disguise skill (as in, physically applying makeup/wigs/etc in order to alter one's appearance), and I'm interested in knowing what's out there.

If this exists in canon form somewhere, could you point me at which book I should pick up? If not, anyone care to share house rules they've used in the past?

It exists in State of the Art: 2063, though we always used Stealth for it until it came around. (Actually, we still do, but shh...)

Made up on the fly:

Disguise
Intellegence-linked
No defaults (maybe Stealth at a +3, but this is very non-canon)
Specializations: By style/type (e.g., Military, Corporate, Tribal, etc.)

Used to make (i.e., design, put together or assemble, but not physically tailor) clothing or costumes that emulate the real deal. Make an open roll and use the result as the TN to determine that the costume is not legit.

Modifiers:
Observer unfarmiliar with the costume type: +1
Observer farmilliar with the castume type: -2
Original available to copy from: +2
Poor source materials: -2
Disguise artist is simply trying to alter his/her own appearance: +3

For simplicity's sake, I rolled mechanic lockpicking, disguise and pickpocketing all into the active skill Larceny: Im fine with pretty generic skills and mentioned activities hasn't come up all that much in our games.

Most skills include a diversity of subskills. The same could be said of someone being world class at designing hardware layouts (Computer: Hardware) shouldn't necessarily be world class at breaking codes or tearing through Red Hosts (Computer: Decking).

T DOC: I think the reasoning behind Seidaku's objection is the same as mine: the basis for the skill in question, in other words, the linked attribute. Stealth's linked attribute is Quickeness, a character's flexibility, agilty, and dexterity. Being able to come up with a costume doesn't seem like a task particularly dependant on one's manual dexterity, flexibilty, or agility; in fact, it seems much more dependant on one's creativity, which is closer to Intellegence or Charisma.

You example works because both the hardware and software elements of computers are based primarily on one's knowledge of how computer systems work and one's reaoning abilities. Imagine, though, that we made "Message Board Interaction" a specialization of the Computer skill just becasue it involves computers. Using a message board involves interacting with other people, albeit in a resticted form (text communication) and at a distance. Still, it requires more social knowledge than raw reasoning skills: it involves the ability to know what to say and what not to say for maximum effect. The only Computer-related skills involved are a basic understanding of GUIs, the Internet, and the ability to type. As such, MB Interaction would do better as an Etiquette specialization, as its primary involved attribute is Charisma (effective interpersonal abilties being a large part of charisma).

This is a bit of an obtuse example, but it should illustrate why it's odd for some to see a creative/intellectual task like making a disguise lumped under a skill which depends quickness. In fact, I'm not a supporter of Awareness being a specialization of Stealth: how aware you are of your surroundings does not depend on your dexterity, agility, or flexibility, it is part of your perceptiveness, which is part of the Intellegence attribute.

Some skills end up getting broken up for game balance --> firearms to the various subsets.

Etiquette gets rolled into one lump skill for conveience.

You just have to decide where "Stealth" falls for your group --> since we're shadowrunners and stealth is fairly common, my GM tends to be a little more literal in the interpretation than other skills.

-Siege