I watched an episode of Alton Brown's Good Eats, so I can't take credit for the idea... but I have some patting on the back for my crazy design. It has lasted for several recipes of homemade bacon, Finnan Haddie, and several other smoked dishes. I have even sometimes diverted the vent and used it as a hot smoker.
I purchased two portable grills on clearance and connected them with a flexible dryer vent. I used heat resistant duct tape to secure. A heat source, such as a hot plate or soldering iron sits in the bottom grill. This heat source is used to smoke/heat up a small amount of dampened wood chips. The food to be smoked will sit on the rack inside the top grill. Depending on what I am smoking depends of the wood chips that I use. For bacon, I use apple wood, hickory, or cherry. Typically for fish, I use alder.
After many, many uses, I've worn out my little masterpiece and now I need to do a little repair. The heat source was too hot burning the dryer vent. It fell apart on my last round of Finnan Haddie and I unfortunately completely burned it.
In the picture above, when making Finnan Haddie or bacon, in Texas heat, I keep a large cold pack on the top grill. Not sure if it does anything or just make me feel better. The top grill is sitting on two inverted planters. I sometimes place it on the backs of two chairs.