that's what i usually do too, but i'm talking about when you only know the tune or melody. i heard the song i'm trying to remember in passing (it was playing in the lobby of one of the hotels i stayed at, and i heard it as i was walking through), and i sort of recognized the tune of the chorus, but i couldn't remember where i'd heard it.
my dad was watching this tech show today and they were talking about programs and websites that are used to find songs through similar sounds/tunes/melodies based on your input (humming or singing)
Midomi was one of them, and i was hoping that i could figure out what the song was, but then found i couldn't even remember how the only part i knew went.
EDIT: holy crap, started exploring more and they actually have Japanese music on here
eek must look more into this...