Someone in one of the Yahoo! knitting groups commented recently that she was stuck on the diagonal. I guess I have been, too. First there was the diagonal baby bib.
Finally, the Diagonal Lattice with Cables Shawl:
This is also almost too simple a construct to be called a pattern, although it is a bit more complicated than the other one. I like working on easy stuff, where size doesn't matter. Therefore, I do a lot of shawls and scarves.