cheap/crafty soundproofing?

[yaymyson.livejournal.com]

i recently moved into a new apartment, which i love. the only problem is that my bedroom window faces the street, and i can hear cars, sirens, and drunkards at all hours. there is a huge tree in front of the window, which helps, but it's still rather loud. is there any kind of fabric i could use at night to absorb some of the sound(a la school of rock), or anything else i could do? please and thank-you.
♥