A few dirt-simple, very cheap DIY homebrew toys:

PET "Ghetto-growler":

Homebrew "pressure caps." Requires a Schrader filler on the CO2 setup, but allows for extremely cheap and effective re-carbonation or "top-off" filling of 2-liter or 24-oz bottles for portability. The innertubes are from a local bicycle shop. They generally have tons of old innertubes that they just throw out, so they're very cheap, or even free.

Due to the possibility of funky stuff leaching out from the vulcanized tire-grade rubber, I generally prefer to keep the bottles upright to minimize contact with the rubber. I've never noticed any off-flavors from it though, even when left for a few days on its side.

These things work great to preserve small amounts of brew for a few days. For instance, you can take a couple 2-liter bottles to a party. If the bottles aren't completely consumed, when you get you can transfer what's left into smaller PET bottles, squeeze the air out, top off with CO2, and put in the 'fridge. No oxidation, no loss of carbonation, and it's good for a week or two until enough O2 leeches through the PET bottles.

Counter-pressure bottle filler:

Homebrew counter-pressure bottle filler. Constructed of small (3/8") copper tubing soldered inside a larger diamter copper tubing (1/2"). The Schrader valve is from a bicycle innertube. The valve stem core was removed, most of the rubber was cut off, and then heated with a torch to burn off the rubber that was bonded to it. After a quick bit of fine sandpaper, it was nice and shiny, ready for soldering. It only goes through the outer tubing, not into the inner tubing. Remove the valve stem core before soldering, and of course lead-free plubming solder only! Note that the rubber stopper looks like it seals around the smaller tube, but it actually doesn't.

I initially simply fit the inlet hose to the CPBF to the outlet of a cobra tap rather than the keg quick-disconnect and ball-valve. This works fine, although you'll need to make sure that the hose doesn't come *off* the cobra tap. If you think about it for a bit, I'm sure you'll realize how bad that would be. :) Also, I had the other parts laying around, so I figured I might as well use them.

Counter-flow chiller:

OK, not quite so inexpensive for this project. Probably about $40 in parts total. I used half of a 25' chunk of "refrigeration-grade" 3/8" OD tubing. To get the best possible heat transfer, I stripped some 14 gauge household wire I had on-hand and soldered it in a spiral around the length. Rather labor-intensive and probably not necessary.

Ends made from a couple standard 1/2" hard copper tubing fittings. This could be ghetto'd up a bit like the counter-pressure filler above to save a few bucks on fittings and 1/2" tubing if desired.

Keep the hose from melting on the final solder with some wet cloth or paper towels.

The finished product (without hose clamps on yet)
Overall, the heat transfer efficiency of this is amazing. With tap water about 50F, I've been able to cool 5 gallons wort down to 70F using less than 10 gallons of water. The downside is that 25 feet of 3/8" OD copper tubing has a fair bit of restriction in it. Having roughly 2-3' of vertical drop from my burner to the carboy, it takes roughly 15-20 minutes to drain all the wort through. Improvements to the design might be to increase the inside tubing diameter to 3/8" ID (more cost), or decreasing the length (less cooling efficiency).