Tunze 9002 with Steve T cup, but this setup goes into the middle chamber vs the CPR that pulls water from the skimmer chamber. There are other skimmers like the Aquaticlife Mini 115 that fit into the skimmer chamber.
For the price I think the CPR would be a great skimmer. The Tunze 9002 also has great reviews in the JBJ 28g. Link below is for the Stevie T In Tank collection cup that fits in the JBJ Nano 28g.
http://shop.mediabaskets.com/Nano-Cube-28_c27.htm