There are many mnemonics for remembering the first several digits of pi, usually by counting the number of letters in each word of the mnemonic. I have yet to hear a mnemonic for the digits of e , perhaps because it's less common to need to know those digits. Most people, as I understand it, mispronounce Aleister Crowley's last name. My enemies call me Crowley because they wish to treat me foully. There are lots of mnemonics specific to particular professions or fields of study.
Many mnemonics take the form of two phrases with similar rhythms.
Sometimes it can be hard to remember the mnemonic correctly and if you get a mnemonic backwards, it's worse than no use. For instance, Feed a cold, starve a fever. Though I gather neither of those is terribly good medical advice anyway. Red sky in morning, sailors take warning. Red sky at night, sailors delight.