This idea comes from Mike. An owner of a local homebrew shop I go to. I haven't made one yet but plans are in the works.
http://www.frugalwestallis.com/index.php
Venturi Tube Wort Aerator
Ever wonder what to do with those old yeast vials sitting around the brewery? I dont. Turn one into a Wort Aerator. If you noticed, they fit the neck of your carboy very well, and screwing the cap onto it keeps it from falling into the carboy. Remember, this item must be used in a vertical position or it will leak wort from the tube, its a gravity thing.
http://www.kettlemoraine.com/mikesbeerpage/images/aerator1.jpg
Heres what you do. Take a 6 inch length of tubing ( vinyl, copper, brass, or stainless depending on your fabrication skills ), drill 4-6 small holes, about .020" diameter into the center 1.5" of it. I used a spiral pattern for the holes, believing that it causes more turbulence, but the aerator tube will work fine with holes period. Drill a hole in the top and bottom of the vial to pass the tubing through, make the hole small enough to fit the tubing snugly. Drill some more small holes for air entry into the cap of the vial, I settled with four one-eighth inch holes. Put a cotton ball just under the lid, this is to be an air filter to keep contaminates out of your wort as it draws the air through and into your wort.
No need to spend money on oxygen bottles or cleaning of those difficult airstones anymore! This is the brewers favorite price point here.... free oxygen! Only one very small warning, if you drill the aerator tube holes too large, wort will leak out of the holes and fill the vial over time. You need to pay attention to the vial if you are allowing pressure to build in the carboy (too tight of a fit in the carboy), wort will fill the vial, soak the cotton and quit working. I now am drilling a 1/16 inch pressure relief / drain hole in the bottom of the vial where it is inside the carboy, venting the air under pressure in from the carboy. They work well in usage, especially if you use a rubber band around the tube to raise it in the neck of the carboy, as I have been suggesting, to increase the fill space in the fermenter before the aerator touches the wort.
WARNING: Do not use this item unsupervised, as you will need to be around to shake down the foam as your fermenter fills, or it will overflow with frothy wort.
Since I started using this device on every beer, I have not had ONE beer finish with high terminal gravities. No stuck ferments, no problems, even when I underpitched my yeast. These are also able to be autoclaved if you use metal tubing.
Follow this picture and you should get one of these sweet gadgets done in less than one hour.
(BELOW) Heres a look at the holes drilled into the tube, there are 4 holes in a spiral around the tube. Only two are shown. There is also a ring of holes in the lid to let aeration air in through the cotton ball filter. More holes than needed (8) are in the shown part. You could use half (4) of that. If you still need to use your oxygen / airstone unit, blast your wort at about 4 hours post pitch, and again at 12 hours, this will give yeast some boost when it needs it according to the yeast doctors.
http://www.kettlemoraine.com/mikesbeerpage/images/aerator2.jpg