I love the limitations that usually come with smaller creative softwares, I feel more engaged when I'm trying to come up with a work-around for something a program can't normally do.
My favourite tool-test so far have been fractals, such a fun way to learn a program's quirks and limitations. My favourite by far has been HTML/CSS/JS though, since each language's role is so clearly stated by a div-based fractal (hierarchy, positioning and style, construction).
