The find command is a very flexible and powerfull tool on the linux commandline. Here are some example usages which are explained on various pages on this site:
find /
used in locate and updatedb to build a search index, and in Speed meets -v to count the files.
find . -iname '*.tmp' -exec perl -i.DontBlameStW -pe "s/Perl/PHP/g" {} \;
used in OGG to MP3, URL-Lists for Google sitemaps, Recursive search and replace
There are many creative uses of the find-command on Advanced techniques for using the UNIX find command.