I could sit around and watch TV and crochet pseudospheres all day long. Here is my second one:
These are fun: they are intellectual without actually requiring concentration while you do them. This one used the last of the Noro Taiyo yarn I had lying around and the same hook as the last one (here).
I started with one stitch in the middle and crocheted two stitches into every three stitches.
I am now working on a hyperbolic plane.