Question

Other than coding for proteins, what else does DNA do?

Answer 1

In addition to so called coding regions which correspond to sequences in proteins, DNA contains many non-coding regions. Many of these are involved in gene regulation. Other non-coding regions probably affect the structural organisation of DNA. The function of non-coding DNA is a poorly understood - but fascinating - subject in molecular biology.

Answer 2

Apart from the many interesting regulatory regions that blues correctly mentions, another thing to think about is where ribosomal and transfer RNA comes from, along with the small interfering RNA.