Another mashup for y'all! This time, it's the production of OPML feeds from YouTube favourites. This uses YouTube's excellent API to get a list of all your favourite videos and render them up in OPML. 
I've tested it in Grazr and it looks really great. I didn't realise that Grazr rendered Japanese (I have a very bizarre Japanese TV show clip in my YouTube favourites).
The URL is: http://tools.opiumfield.com/youtube/faves/[username]
As an example, here's mine, and you can preview it in Grazr.
This is only the first of a set of YouTube-related mashups, I hope. It's even got Technorati support built in based on my previous mashup. I may also add another feature in the morning (wait and see!).
I built this mashup using Keith Devens' excellent PHP XML Library, which handles most XML brilliantly. I'm looking for other libraries to handle the few exceptions that Keith's scripts can't read, but it's a pretty good start. As for time, it took me about an hour and a half. I'm no expert on the Valley, but I can see how Web 2.0 kicked off, considering how easy it is to get these APIs to work.
In the morning, I'm going to work out my strategy for building other mashups and sketch out a brief timetable until I launch my mashup aggregator and you can get your own opium field to play in. 
