tuning by ear

[billy freedom]

most toilets flush in Eb

 

most car horns are in the key of F

[Mark Werner]

For those of us with less-than-perfect hearing (childhood ear infections and adult shooting...) the electronic tuner is a godsend.
Even well-known musicians have problems; Chet Atkins related that he was terrible at tuning and considered giving up the guitar...But by then he'd made so much money that he couldn't quit.

[billy freedom]

this is a free chromatic tuner for pc http://download.cnet.com/AP-Tuner/3000-2133_4-10342381.html
i dont like it but you can tune a piano with it etc.