To quickly find any text string within any text file, try this from a terminal window:
grep-l[text to find][files to look in]
For example, grep-l 123abc *.html will list the name of any filein the current directory that ends in .html and contains the string 123abc.
(That's a lower-case-L following the GREP)
Quite powerful, and fairly fast. Now, if you have some spare time, and want to see what it can really do, try this:
su root
cd /
grep -lr "text to find" *
This will tell the OS to find the "text to find" in every file in every directory, all the way down through the tree. The -r flag tells grep to recursively search directories.
Of course, OS X has something like 26,000 files, so this can take a very long time!