I have been pretty apprehensive about posting this, due to the ghetto-ality of my own diy project, but I have had great success with a homemade version of the sander's piccolo skimmer. The idea is thus: Take a water bottle, preferably a narrower, tall type, which is about 2 1/2 inches in circumference and about 10 inches tall. Cut the bottom inch to inch and a half off of the bottom, saving the bottom piece. Put a small lee's airstone in the container at the lowest point of the open bottle by cutting a small hole about one half of an inch from the bottom, the hole being the size of an airline tubing. Take the bottom cutoff piece and cut a hole in the center of it, roughly the size of the bottle mouth. This will be the collection cup. Put the "collection cup" on top of the mouth of the bottle, I cut mine the same size of the threads the cap went onto, then twist it on and seal it with silicon. Add airline and pump and submerge the open end. Now, mind you, I have mine sitting in the first compartment of my eco 40 hang on, so it is cleverly disguised, but I think that this will work with any hang on fuge, small power filter, whatever. The level of the water in the chamber needs to be fiddled with, but a good starting point is about 2" from the top of the mouth. Mine produces a good dry skimmate all the time, and is way more effective than it sounds. If you just had it in your tank, a pair of cable ties and small suction cups would aid in positioning it on the glass. Also, a piece of plastic or whatever will need to be placed over the collection cup as well, as you will find (as I did) a tall tower of foam sticking out of the mouth of the thing in no time. Give it a try, it's tiny,it does work, but it is kinda ugly.
Good luck!
Joey