What about adding additional tags or attributes so we can filter by length of time, date published (vs date submitted to your site), publisher (npr, radiotopia, etc), guests (i.e., i liked this guest on Marc Maron's podcast, where else can I find him?), or sub-genre (i like true crime podcasts and sometimes I get that on Criminal, sometimes I get that on This American Life)

Totally agree, length would be hugely useful so you know what you're getting into! :)

good suggestions, I'll think about implementing some of these!

I actually use these sites (mostly Yummly, but I always try new ones), and I have a comment that applies to all of them. It has to do with the variability of the underlying data.

Do I have "parmesan" or "parmesan cheese" or "parmegiano reggiano" or "parmegiano-reggiano"? Also, there is an implied hierarchy to some ingredients. For example, if I have fresh lemons, then I have "lemon juice" and "lemon zest" and "lemon peel".

I don't really know how this site or any others like it handle those types of things. Maybe its fixed behind the scenes, but a visual indicator would be great.

The other problem is substitutions. If for example I have Parmesan, feel free to show me recipes calling for Grana Padano or even Pecorino.

Yep, agreed.

It's probably a lot of work to build these relationships up front.

It's probably easier to allow the user to make their own relationships. In other words, when I search for "lemon", give me the ability to easily roll up "lemon juice" and "lemon peel" and "lemon zest". Make this a one time activity and have it save to a profile (also, easy incentive for users to create an account).

You can monitor all of your users' custom relationships and curate the good ones. Automate this for common relationships, i.e., if 50 people build the same lemon relationship, push it out to all users. You could make it opt out as an advanced setting for the purists I suppose.