Using Calibre:
You'd need Calibre to be running permanently on your PC and you'd need to schedule various rss news feeds ie just enter the url of the feed and how often you want Calibre to read it. Then under "Calibre > preferences > email delivery" just enter your Kindle email and the feeds should appear magically on your Kindle.
Using Feedbooks:
feedbooks allows you to create a newspaper of various rss feeds (your subscriptions) and it then packages them into a mobi document. You initially download the first copy via usb cable but you can have the newspaper emailed to your Kindle email account on a regular basis. If you don't want the charge then there is a link in the mobi file to download the latest copy.
I've tried it with mixed results but essentially it works. The creator of the site is a regular on the forum.
Note : Amazon imposes a small charge to send data to your device via email.