Ah, the good old chopstick shoved in the tubing method. I remember that used to be a popular way to do things a few years back. People would stick the make shift diffuser right underneath their intakes and outflows to help with the dissolving the bubbles. It's not the most effective method, but it worked somewhat an alternative to in the tank powerhead based reactor that was also common at the time.
But yes, now that we are in the year 2008, we can get a glass nano diffuser. They work great with DIY CO2 Setups.
-John N.