Here are some suggestions for improving UserLand Radio.
Category post to e-mail – I subscribe to many mailing lists. Discussion topics of those mailing lists frequently overlap with my blog categories. For example, my Online Payment category and the 3d-secure mailing list. When I post a message on either one, I usually post on the other as I have done with my Extending 3D-Secure post. So, an optional Radio feature that automatically does this would be convenient.
Category post to Usenet – same as above except post is made to Usenet.
Private Category to Public Categories – while most news aggregation is happening at the client end, there is room for intermediate news aggregation that aggregates posts from multiple blogs. User can set this up by specifying one or more post destinations, each corresponding to a Public Category. This feature leads naturally to introduction of editorialized news and invited columnists.
Syndicated News Filters/Prioritizer – I subscribe a good set of RSS feeds, but I am usually interested only in certain topics. It would be nice to be able to filter or sort news by requiring presence or absence of certain words and phrases for each subscribed RSS feed. Also, it would be great if I received regular reports of words and phrases my RSS feed subscribers are interested in.