I've spent a lot of time thinking about a good way to take samples for beer in progress to check gravity. I bought a 50ml volumetric pipette but it was quite slow to fill and took 2 cycles to get the 100ml I needed to float the hydrometer. I have looked at devices like the wine thief and didn't feel like spending money on something I felt should be very cheap also it was more then I wanted to sanitize every time.
The result of this is the Vacuum Beer Bleeder for about $2 in materials, an empty soda bottle and cap you to can make the greatest breakthrough in beer sampling technology!
It goes like this you need 2 1/8" x 10-32 hose barbs (McMaster Carr 5454K62) and about 3' of 1/8" ID tubing. Now drill two holes in the plastic bottle cap just small enough to force thread the fittings into, if you want to get fancy break out the tap set. Keep in mind that these holes need to be close enough together that you can still thread the cap on. Now screw in two hose barbs and shove some tubing on. I like to cut one tube short just so I know which one to stick in my month.
When you need to sample just stick this cap assembly in sanitizer, drain and screw on an empty soda bottle. Now stick the long hose in the beer and the short on in you mouth and suck until you have drawn what you want.
Here are some images of the finished product....