The default RSS feeds for reddit leave a bit to be desired.
This filter allows you to filter out entries from a reddit feed that have fewer than a specified number of comments. By default, the number is 0, allowing the full feed through. However, you can set that number to a threshold you like so that only somewhat discussed items make it through the filter.
It also orders them by number of comments, with the most-commented-on items appearing first in the feed.
Pipe Web Address: http://pipes.yahoo.com/rodhilton/redditfilter