At the moment the plugin can display one of two data sets: The hot events on joind.in; or the talks from an event on joind.in. You can change the title on the block, limit the maximum number of records returned, specify which event the talks should come from and also indicate if you'd like the order randomised. You can see the plugin in action on techPortal, where it is picking a few sessions at this year's Dutch PHP Conference to tempt you with!
I hadn't written a wordpress plugin before although I was very familiar with the joind.in API and how to work with it from PHP. The plugin was relatively easy to write, there are plenty of tutorials on the web and I didn't need to do anything particularly clever. I looked at a twitter plugin, tweetblend, which was a similar sort of idea in that it had settings, talked over an API, and stored data, and used that when I got stuck. My plugin is much simpler but that's OK (and probably makes it a good example for me next time I want to write one of these things!!)
The plugin creates a database table when it is activated (and drops it when deactivated) which caches the data pulled from joind.in for a few minutes. This helps avoid lots of users having to wait for the data to load and also hopefully stops the plugin from pushing too much load to the joind.in servers. Since there is no limit or pagination on the joind.in API, even though only a few records are shown the whole result is cached. This means that if you turn on the randomise then the cache is still useful! The "random" is a bit contrived in that it just picks elements out of the array that haven't been used but it looks fine to me.
Initially I was just going to put something together and upload it to the techportal site but I was persuaded that it would be a useful thing to share - so there it is. Comments and suggestions are all welcome - and if you are using it to publicise your event, let me know!