Need an r but have 10 ps left? Turn that p into an r with just a few cuts. Save that little extra you cut off, it can transform a c into an e. I've even used a marker to transform a letter into another one and no one was the wiser.
Make a ransom note title. Mix up those letters and use them from a bunch of different alpha sets. You can do this word by word or mix up the letters within the words. Either way looks great!
The easiest way to use up all those extra Zs is on a layout of a sleeping subject.
Doing a layout of your child reading or practicing handwriting? Use a solid paper and use up your alphas creating a background.
Use your o, O, 0 and 8 to make the base for an embellishment with brads, buttons, flowers or whatever you have on hand.
If you have more ideas I'd love to hear them or see some examples. I still have a large folder of 1/2 used alphas and now that I have my die cut machine it collects too much dust.