Open Source Solutions

Tiny Tiny RSS is a web-based news feed (RSS/Atom) aggregator, designed to allow you to read news from any location, while feeling as close to a real desktop application as possible.

Newspipe is an RSS/Atom aggregator with a difference: It allows you to keep track of your feeds through e-mail - you create an OPML file listing your feeds and Newspipe will collect them, convert them to e-mail messages and send them to your mailbox.

This smart script sends the contents of a single RSS feed to an email address, in less than 50 lines of PHP. It requires Magpie RSS and Php Mailer to parse a feed and send an email.

The author also explains in other very interesting paper how he daily deals with feeds, using this script.
Why I´m Loving IMAP and Thunderbird as my RSS

[...]
an article by J. Wynia
http://www.wynia.org/

A XML-based RSS parser / reader in PHP. Supports most RSS versions including RSS 0.9 through RSS 2.0 and Atom. Supports modules, and namespaces.
http://magpierss.sourceforge.net/

> Many online feeds agregators use Magpie:
- Gregarius
http://devlog.gregarius.net/
- suxOr
http://sourceforge.net/projects/sux0r/

Simple yet powerfull PHP RSS parser / reader. Works as a PHP class and supports RSS 0.9x, RSS/RDF 1.0 and RSS 2.0. It uses regular expressions instead of a XML parser and returns an associative array of RSS fields as a result.
http://lastrss.webdot.cz/