Use your smartphone. Smartphones have apps such as Shazam, Midomi and ScreenTunes that will help you identify a song by a small sample. Launch the app from your phone and ask it to ID a new song while holding your phone's microphone up to the speaker the song sample is playing from. The app will provide the song's artist and title, giving you the information you need to find the song for personal use.
Visit lyrics websites to help you identify a song sample. Websites such as LyricsPlanet.com, LetsSingIt.com and LyricsMode.com allow you to type in the lyrics you heard -- or think you heard -- and it will give you the full song as well as a sound sample to compare what you think you heard with the lyrics search results.
Search the Web. If you are still having problems identifying the song by the sample you heard, launch your favorite Web search engine and type in the lyrics you think you heard. If that is still not enough, you can search by where you heard the sample, such as "song on Fago yogurt commercial" or "summer 2009 Gap commercial song."