Convert a folder full of screenshots into well-named JPEGs

I like using Grab for Mac to quickly capture a bunch of screenshots when I'm documenting the user journey through a web project I'm working on.
Here's a short workflow I made to convert a folder full of screenshots (named "Untitled 1..23.tiff" etc) into neatly-named JPEGs, ready for insertion in a markdown doc.

mv -i Untitled.tiff 1.tiff
rename 's/^Untitled //' *
rename 's/^(\d)\./0$1./' *
mogrify -format jpg -resize 1280x960 -quality "90%" *.tiff

See also ImageMagick: Command-line Tools: Mogrify.