Create a simple spelling checker for text files.
Design Questions: Auto-generate output files names? Write output files to a special directory?
When you find a misspelled word in a text file, ask the user what to replace it with.
Design Questions: Accept a word's spelling and move on? Temporarily add the misspelled word to the list of words used on the current file?
Create a simple spell checker for Python code files. For example, only spell check strings and/or comments.
What about other computer programming languages?
Download a word list from the web.
Perhaps find/create a specialty word list containing jargon for a particular profession, group, or trade.
Note: Years ago I downloaded and used a 70,000+ word list. How would this effect your spell checker design?
SCOWL
(Spell Checker Oriented Word Lists)
is a collection of word lists split up
in various sizes and suitable for use in spell checkers.