> Can you make a top-ten?

Aliases:

split-string aliased as string-split
downcase aliased as string-downcase
upcase aliased as string-upcase
format aliased as string-format
concat aliased as string-concat

New functions (with string- instead of s-):

s-truncate (len s)
s-chomp (s)
s-left (len s)
s-right (len s)
s-repeat (num s)
s-capitalize (s)
s-reverse (s)
s-contains-p (needle s &optional ignore-case)
s-blank-p (s)

Nice to have, but do not really care:

s-index-of (needle s &optional ignore-case)
s-center (len s)
s-pad-left (len padding s)
s-pad-right (len padding s)
s-chop-suffixes (suffixes s)
s-chop-prefixes (prefixes s)
s-shared-start (s1 s2)
s-shared-end (s1 s2)
s-prepend (prefix s)
s-append (suffix s)

Hope it helps,
Philippe