The number of scientific SE sites is increasing steadily currently we have for the natural sciences: Statistical Analysis, Math, Theoretical Computer Science, Physics, Skeptics, Astronomy, Theoretical Physics, Computational Science, Biology and Cognitive Sciences.
One feature that would be useful to all of these sites would be making it easier to cite scientific literature.
A proper citation of a scientific paper to support your answer would look roughly like this
According to Nikolova et al.1 DNA can form transient Hogsteen base pairs ...
DNA can form transient Hogsteen base pairs (Nikolova et al. 2011) ...
All citations would be listed at the end of the post and if available the citation in the text itself as well as the full citation in the list would be linked to an online source of the reference, preferably via DOI to avoid link-rot.
Of course it is already possible to achieve this effect manually, but it is a lot of work to properly format the citation in markdown. It would be very nice if the citation could be generated automatically from a BibTeX or RIS file, those are usually available directly on the online version of the scientific article, or can be easily exported from a citation management software.
Another way to get the bibliographic data for papers form the life sciences would be the Pubmed database.
My idea is that this would not only make it easier to add proper looking citations, making the sites look more professional as a whole. but that it would also increase the expectation in regards to citations. It should encourage users to back up their claims with primary literature and improve the quality of the answers.
An additional idea would be to use the citation data for the "Linked" or "Related" block in the sidebar. Posts that cite the same sources (determined e.g. by comparison of the DOIs) are usually about closely related topics, and making it easier to find them might be very useful in some cases.