If you have Photoshop, there's a link to how to apply a gradient effect on text here.
http://www.createblog.com/photoshop-tutorials/1242-how-to-make-gradient-text-in-photoshop/

Play around with it and you'll probably be able to get it to look like a rainbow.
There also seems to be some other effect, too... You can try using a "chrome" effect?

This is the cover to Catcher in the Rye. Does anyone know if there's a look-alike font for it? Thanks!

There are multiple fonts here. I can only remember 2 of them:

Bleeding Cowboys: http://www.dafont.com/font.php?file=bleeding_cowboys
Broken Ghost: http://www.dafont.com/broken-ghost.font

Hopefully you can find the others, or I gave you the ones you wanted.

I believe this is the font

Here you go!