Morse code mnemonics are systems to represent the sound of Morse characters in a way intended to be easy to remember. Since every one of these mnemonics requires a two-step mental translation between sound and character, none of these systems are useful for using manual Morse at practical speeds. Amateur radio clubs can provide resources to learn Morse code.
Cross-linguistic
A technique to help learn Morse code, part 1 of 3 - This topic covers mnemonics for the alphabet. See http://ece.uwaterloo.ca/~dwharder/Morse_code for a pdf. Some improvements: use "gym" for "G" (starts with "g" unlike "Age"), "else" for...
Visual Mnemonic
Visual mnemonic charts have been devised over the ages. Baden-Powell included one in the Girl Guides handbook in 1918.
Here is a more up-to-date version, ca. 1988:
Other visual mnemonic systems have been created for Morse code, mapping the elements of the Morse code characters onto pictures for easy memorization. For instance, "R" (ââââââââââ) might be represented as a "racecar" seen in a profile view, with the two wheels of the racecar being the dits and the body being the dah.
English
Syllabic mnemonics
Syllabic mnemonics are based on the principle of associating a word or phrase to each Morse code letter, with stressed syllables standing for a dah and unstressed ones for a dit. There is no well-known complete set of syllabic mnemonics for English, but various mnemonics do exist for individual letters.
Slavic languages
In the Czech language, the mnemonic device to remember Morse codes lies in remembering words that begin with each appropriate letter and has so called long vowel (i.e. á é à ó ú ý) for every dash and short vowel (a e i o u y) for every dot. Additionally, some other theme-related sets of words have been thought out as Czech folklore.
Indonesia
In Indonesia, one mnemonics commonly taught in scouting method to remember Morse codes lies in remembering words that begin with each appropriate letter and substituting the o vowel for every dash and other vowels (a, i, u, and e) for every dot.