So after my first experience with slants in test tubes, which was less than successful, I think I've got it figured out much better.  I bought these 1 dram (1/8 fl oz) glass vials on eBay.  They're practically the perfect size for a slant (not excessively tall like test tubes), have flat bottoms so they stand up on their own, and have screw caps so the yeast doesn't blow the tops off when it grows, if left somewhat loose.

With my labelmaker I made those perfect labels for them, with the yeast type, brand, strain, generation number, and date of culture.  I've learned my lesson after pulling an unmarked tube of yeast out of the fridge and throwing it away because I forgot what type it was.

I'll put together a how-to article on the process as soon as I've got some more experience with it, to make sure everything goes well.