bill - 2:47 am on Mar 27, 2009 (gmt 0)

Look at the feeds from major news or technology blogs. They have hundreds of items sometimes. You might want to limit the size of the feed if it became too large for your visitors to download though.

The other thing you want to keep in mind is that your feed is a service to your users that lets them consume your content in another way. It gives them a heads-up when something new happens on your site. It's a reflection of the activity on your site. Don't artificially inflate the feed.