Tongue twisters are also a part of literature; good tongue twisters are those that are challenging and make witty sense at the same time.
Here is a pretty extensive collection (“1st International Collection of Tongue Twisters”) of common ones as well as not-so-common ones: http://www.uebersetzung.at/twister/en.htm
Tongue twisters are a good way of training your articulators in English enunciation. Meanwhile, words that sound alike usually look alike as well, so trying to understand the tongue twister helps you become more aware of the nature of English words and their nuances. In particular, tongue twisters often make use of words with multiple meanings, for example those that refer to more than one object or those that can be both a noun and a verb at the same time.