Saw this over at bioinformatics.org...
Bioinformatics - Online Modular Degree Program
They have modules that earn you credits towards :
Certificate Program
Diploma Program
Masters Program
It looks like they have tracks for both those with a science background and those who have a computer science background. I looked into John Hopkins U. Their program looked much more competitive and required a life sciences undergrad degree.
Take a look at the attached PDF.
For more info check out the link above or the forum announcement