If you like to have a new look for your feed icon visit Zeusboxstudio.com. There you can download a set of feed icons in 32 and 16 pixel sizes. All icons are in PNG format and are free to use.Here is another one which include standard and colored feed icon. Package includes 50 12x12 colored icons based on Adobe Photoshop's default color palette.

And if you want a web2 style feed icon visit this link

Here is an online RSS button maker. You can create your own RSS styled buttons there.