I wrote earlier about Data Nuggets, a great website for helping students connect math (and understanding how it is used in research) with science. Here are two other teacher-focused websites that offer real data sets from real research along with help introducing data analysis to your students.
Science in the Classroom is put out by AAAS and includes several articles with supporting information and data charts for teachers. I was especially interested in this article on the cell’s response to mutation, because I could see using it with students studying replication and genetics.
HHMI’s data points takes a slightly different approach and focuses on one graph or figure from an important piece of research, and gives suggestions for helping students process it. Visual literacy is critical for science students, so this seems like it has a lot of potential. Here’s one on predator-prey relationships, and another on the growth of the microbiome after the Deepwater Horizon oil spill.