I do not like the default search engine that has Ubuntu. He finds nothing, so it takes me less searching by hand to using a search engine. Sometimes Synapse use the search box that works pretty well, but still fails. That's why I liked this program that really meets the mission of finding files on Ubuntu, using different search engines.
To install on Ubuntu writes :
sudo apt-get install catfish
For Fedora writes :
yum install catfish
You can access it from Applications/Accessories/Catfish:
You can make a selective search folder and choose the file extension you wish to search. Also included in the search for hidden files. And most importantly: It works great!