Well there's the typical homemade: 2-liter bottle, hole in the side, emptied bic pin as a downstem and tin foil as a slide. That won't really last all that long. So here's how to make a really good bubbler/bong. Pics are taken off photobucket, not mine.
I worked hard on this man, so don't take it for grantedStep 1. Find a pickle jar or similar small-medium sized jar like the on pictured below.

Make sure that the jar is COMPLETELY clean. SQUEAKY and SHINY clean. Put it through the dishwasher if necessary.
Step 2. (Not Pictured) - Puncture two identical holes in the jar lid, make them on opposite sides of the lid about 2-4 cm from the edge. They should be 1-1 1/2 cm in diameter.
Step 3. Fill up your jar 2/3 to 3/4 of the way with pure water.
Step 4. Find 2 BIC pens, like this:

Take out the inside parts so you end up with two thick plastic straws. Stick them both in each hole. Put one down into the water about 5-7 cm. This is your downstem. The other one should be higher up in the jar so that it does not touch the water.
Step 5. At this point you should be able to suck through the straw not touching the water and produce that characteristic bubbling noise. If this doesn't work it is likely that there are holes in your plan (lol).
First ensure that the lid is screwed on very tightly, and that no air is escaping through the screw area. (XD)
Now look at your two straws, chances are the holes you drilled are too big. Correct this by using gum, wax, tape, aluminum foil or glue to make an airtight seal. Make sure whatever you use in non-toxic.
Step 6. Now take aluminum foil and make a bowl with a long thin part on the end, stick it into the straw that reaches the water. Create an airtight seal using the same methods mentioned previously.
Step 7. And there you have it, put your smokeables in the bowl, light 'er up and puff away. Additional things you can add are:
+Covering the entire thing in tin foil, for some reason I like doing this.
+Adding a filter to the bowl.
+Burning the straw that doesn't reach the water and bending it away from the bow so the mouthpiece is curved.
HAVE FUN, and if you decide to do this, please take pics