Things that only tailors can make for other people.
2 epic cloaks that are some of the best in the game = lots of money and a good starting place as a raider.
3 epic gloves that are pretty much the best pre-raid = lots of money and a good starting place as a raider
3 epic chest pieces = same as a above.
2 epic spellthreads that are some of the best leg enchants in the game = lots of money to be made as well as helpful to your guild.
3 epic cloth pieces for frost resistance = probably going to be mandatory for several things throughout WotLK = lots of money to be made, and again, usefulness to your guild.
And let's not forget one of the most important things of all.
Creators of 22 slot bags = You will be making large, stable amount of money, for the entirety of the expansion.