Skills:
Tailoring : As a tailor you can make many a gorgeous and unique outfit. Many people don't keep a lot of the lower level outfits and shirts as they level because they get bigger and better gear. SO and inexpensive and personal present would be to make an outfit! For a female char i would recommend a white woolen dress. For a male character Blue overalls with a Workman's shirt always bring a smile.
Engineering: For any engineers I would recommend going for something worth a smile. The cheaper options would be things like the mechanical squirrel , frog and chicken !
Jewelcrafting: For a jewel crafter a little more effort is required. One thing i would suggest is heading onto the armory and looking up the gear of the person receiving the gift. then you could perhaps see if you could upgrade any of their gems!
Alchemy: We all know how expensive potions and flasks are at the moment so if your an alchemist a little flask of potion could be the perfect gift for someone. Find out what abilities they value most and make a flask/potion to boost these skills! If you don't want to ask then an all round improved stats potion would be great.
Cooking: There is one truly lovely thing to get as a present, and that is a chocolate cake!! The fantastic fireworks and happy feeling would really be a great present for anyone in wow epic or newb!
Ah:
Oh the fantastic world of the auction house, it can make or break your bank! Heading to one of the mutual faction auction houses such as the booty bay one can really be great for finding unique gifts! I am always searching the miscellaneous section for new and interesting things for guildies!
Don't forget a lot of the crafted items listed above can also be found on the Ah!
So why not give it a go, and i would love to hear about any unique gifts you can find!