This page led me to rediscover the name of the digit-to-consonant mnemonic system I absorbed from the 2000-vintage internet (probably Everything2): the Major System [1].
Fittingly, I'd forgotten the name of this technique, though I still sometimes absentmindedly perform it on phone numbers and other digit strings in my environment when I'm walking around or whatever.
Basically, you map the digits 0 through 9 to specific consonants, then come up with vowels to build out phrases that are more memorable than a bunch of boring numbers. I think I stopped practicing the system around the time I started storing phone numbers in cellphones, but reading this has reminded me to pick it back up and see if I can find any practical uses.