Heavy metal beads are great for making tilt sensors. They can be used in combination with smaller metal beads or non-conductive glass, plastic or ceramic beads.

You can also make your own conductive beads, either by shaping them from some stiff metal wire and possibly soldering them to add enough solder to make them heavy. One [...]

The circuits found inside cheap electronic toys, especially sound toys, can become very useful when you want small circuits. You can not customize them as much as planning and programming your own, but these come cheap, quick and easy to cut down to a bare minimum and embed in a garment.

from Wikipedia:
also: Lithium-ion polymer batteries, polymer lithium ion, Li-poly, Li-Pol, LiPo, LIP, PLI or LiP
Rechargeable batteries which have technologically evolved from lithium-ion batteries. Ultimately, the lithium-salt electrolyte is not held in an organic solvent as in the lithium-ion design, but in a solid polymer composite such as polyethylene oxide or polyacrylonitrile. The advantages of Li-poly [...]

A series of custom made plugs to be sewable or soft.

Roland MDX-40
With engraving drilling head, you can produce your own PCB. It can not make copper lines thinner than 1.6mm, but enough for DIP circuits. Great thing is that you can skip the messy etching process.

>> Obi
>> Local hardware store

also: chloroprene
neoprene is the trade name used by DuPont Performance Elastomers. A synthetic rubber that is produced by polymerization of chloroprene.
Sedochemicals produces sheets of Neoprene in the following qualities. For most of our sensors we use 1.5 mm thick HS quality neoprene with standard polyester jersey fused to either side.
Check the Sedochemicals website for details [...]

also: iron, quilting iron, mini iron
Comes in handy when ironing small pieces. Fusing fabrics together.

This tape is nice for isolating contacts, especially when you keep forgetting to thread the wire through the shrink tubing before soldering it.

We have so far unsuccessfully used graphite powder to make our own stretchy conductive glue or paint. But it is possible to make non-stretch glue/paint by mixing graphite powder and liquid tape together.

Conductivity similar to water.

There are many ways to do wireless communication. When developing wearable technology project, it tend to come in play. At the moment, xbee is our favorite, although there are many other ways to do wireless communication.

Sparkfun made a great comparison on wireless modules. 
Sometimes you do not need large data rate, or you need something that [...]