Creative Dojo has a video tutorial on Dynamic Auto Resize & Auto Scale text
This is very cool, and very useful for making templates, especially in commercial, direct response and web video advertising. Make sure to subscribe to Creative Dojo on YouTube.
Expressions are amazing, and I wish I was better at writing them instead of just using them, and this goes through the expressions so you can get some information about how it works.
ECaBrams on using Random Expressions in After Effects
A very useful lesson on adding randomization in After Effects.
You should check out the rest of ECAbrams videos on youTube as well.
I really need to dive more into expressions. I can use them and do some modifications, but I am not really an expert or good at creating my own, which is something that really can bring master levels of After Effects.