I agree on the Syndontis, there are also crabs that are found in the African lakes (but I don't know if they are suitable for a community tank).
I don't think I'd mix anything but a very large pleco with most of the South American species (at least any of them over 6"), and with some of them I'd think twice at that.
EDIT: And I like my tilapia with lime and ginger, served with a green salad.
