Rosalind is a beautiful online tool that lies at the intersection of “people who like solving bioinformatics problems”, “people who like structured learning curves” and “people who like receiving experience points and levelling up for their efforts”.
Basically, you make a username and start with the simplest problems – the first one is to count the occurrence of different nucleotides in a string. As you solve the simpler problems, the more difficult ones become unlocked, and the progression teaches you programming concepts in the process. In case you’re worried these will be too simple, the more advanced problems do include things like multiple alignments and phylogeny comparisons – there’s probably some interesting stuff here for most people.
Most importantly – it’s fun, and it’s addictive. Check it out!