ROSALIND: an addictive bioinformatics learning site
I just learned about this one: ROSALIND is a really cool concept in learning bioinformatics. You are given problems of increasing difficulty to solve. Start with nucleotide counting (trivial) and end with genome assembly (not so trivial). To solve a problem, you download a sample data set, write your code and debug it. Once you think you are ready, you have a time limit to solve and provide an answer for the actual problem dataset. If you mess up, there is a timed new dataset to download. This thing is coder-addictive. Currently in Beta, but a lot of fun and seems stable.
More problems to come, and they also have post problem-solving discussion boards (no, you cannot take a peek at the answers), and a discussion board for new problems. From their “About” page:
The project’s name commemorates Rosalind Franklin, whose X-ray crystallography with Raymond Gosling facilitated the discovery of the DNA double helix by Watson and Crick. [...]
Rosalind is a joint project between the University of California at San Diego and Saint Petersburg Academic University along with the Russian Academy of Sciences. Rosalind is partly funded by a Howard Hughes Medical Institute Professor Award and a Russian Megagrant Award received by Pavel Pevzner.
Did I say addictive? Yes. Make sure you clear some time for this one.