Feedtwister is a great source for mashing multiple RSS Feeds

In a nutshell, this is what you can do:

Mix your favorite feeds and show their latest posts on your website.
Create as many lists of feeds as you want.
Add up to 50 feeds per list.
Assign an image to each feed.
Choose the output charset encoding.
Order posts by date or title.
Limit the posts shown and establish a posts per source maximum.
Fully customize how the posts are displayed with our template system.
Data is cached so it loads fast and updated so you get the latest info.

Here are my Feedtwisters:

Why use this tool? It’s a great srouce for syndicating your blogs on your website, in your social networks, and you get listed in a directory. You never know who is interested in your posts.