Why are there only three ...
Question: Why are there only three songs nominated this year, and has that ever happened before?
Answer: The reason has to do with the current nominating practice for songs, which involves an averaged point system. Only songs that get an average score of 8.25 or better are eligible for nomination, and of the songs from 2005 films, the only ones that succeeded were "In the Deep" from Crash, "It’s Hard Out Here for a Pimp" from Hustle & Flow and "Travelin’ Thru" from Transamerica. That said, there's also a stipulation that there have to be at least three nominations and no more than five, so if only two songs come up to snuff, there must be some back-up plan to get a third on the ballot.
Those are the rules now, but in the past they were clearly different: In previous years there have been as few as three song nominees (as far back as 1934 and as recently as 1988) and as many as 15.