Fill in for a period. You don't need the title right away. Paul McCartney entitled one song "Ham and Eggs" until he came up with "Yesterday," the most recorded song in the history of the record industry.
Think about what the song means to you. Identify the driving idea behind the song. It could be a person, place, specific memory, statement on a philosophy or ideology. When you've found the idea behind the composition, try to distill it into a couple of good words that will make a nice title for your song.
Read the lyrics repeatedly until something pops out at you. Maybe it's a phrase in verse one, or something loosely based on the chorus. Your lyrics will give you clues for possible titles.
Research the subjects of your song for other proper nouns that might make good titles. If you're into really artistic sounding titles, take the people and places in your song and run them through the Internet to find other historic names or titles that you might be able to use.
Go for a wacky, over the top titles. Lots of musicians love to randomly title work with words they find amusing or clever. You can dream up a wacky title in seconds, but think twice before using it. While it might seem great to you, lots of fans can find random titling gimmicky.