There are a bunch of string methods listed over at W3Schools.
Here are some I particularly like:
count() - Returns the number of times a specified value occurs in a string
find() - Searches the string for a specified value and returns the position of where it was found
index() - Searches the string for a specified value and returns the position of where it was found
isalnum() - Returns True if all characters in the string are alphanumeric
isalpha() - Returns True if all characters in the string are in the alphabet
isdecimal() - Returns True if all characters in the string are decimals
isdigit() - Returns True if all characters in the string are digits
isnumer() - Returns True if all characters in the string are numeric
isprintable() - Returns True if all characters in the string are printable
lstrip() - Returns a left trim version of the string
replace() - Returns a string where a specified value is replaced with a specified value
rfind() - Searches the string for a specified value and returns the last position of where it was found
rindex() - Searches the string for a specified value and returns the last position of where it was found
rstrip() - Returns a right trim version of the string
split() - Splits the string at the specified separator, and returns a list
startswith() - Returns true if the string starts with the specified value
strip() - Returns a trimmed version of the string
zfill() - Fills the string with a specified number of 0 values at the beginning
