I'd inadvertently downloaded a lattice multiplication app a couple weeks ago and thought "Huh?" when I looked at it. But yesterday I watched the Khan Academy video on lattice multiplication and now I'm sold!
I'd never heard of it before, but I think it is a really nice way to do multiplication of multi-digits. Better than remembering the 0 in the standard way--so nice to do all the multiplying then all the adding. Plus it's kind of fun. It feels like it is too tricky to actually work, but it does.