I guess the recommendations will depend a lot on what people are interested in.

I'm interested in talks where people don't talk about their project itself, but about how they solved the problems encountered while developing it (i.e. where I can learn something for my own project).

I'll offer a recommendation: "Optimizing Firefox: Why Large Applications Start Slowly" which was useful even if you don't care for Firefox.

Any others like it?

Glad you asked, I did a short write-up of the talks I liked on my blog: http://mapleoin.eu/perma/FOSDEM-2012-review

I especially recommend The Apache Cassandra Storage Engine talk if you're interested performance optimizations/caching and that sort of thing. The talk is really easy to follow with no prerequisite knowledge about Cassandra.