Rosalind: Learn Bioinformatics Online Through Problem Solving

I was introduced to Rosalind, a problem-based Bioinformatics Tutorial website, and I think it’s fantastic.  I wish I knew about it when I was first starting out.  You can solve the problems in any language you want.  The website does not run your code.  It only grades your solution dataset.  There are a large number of problems on different topics, from codon-finding to protein spectrum matching.  I would say the problems are geared towards the beginner, but there is enough variety that a higher level bioinformaticist would also benefit from rounding out their knowledge.