Earlier this week Alex Ball and Monica Duke from the Digital Curation Centre released the how-to guide Cite Datasets and Link to Publications (https://web.archive.org/web/20120525040549/http://www.dcc.ac.uk/resources/how-guides/cite-datasets?). The guide is highly recommended reading for everyone interested in data citation. The guide was released under a Creative Commons Attribution license (https://web.archive.org/web/20120525040549/http://creativecommons.org/licenses/by/2.5/scotland/?), allowing me to post the summary for researchers below:
If you have generated/collected data to be used as evidence in an academic publication, you should deposit them with a suitable data archive or repository as soon as you are able. If they do not provide you with a persistent identifier or URL for your data, encourage them to do so.
When citing a dataset in a paper, use the citation style required by the editor/publisher. If no form is suggested for datasets, take a standard data citation style (e.g. DataCite’s) and adapt it to match the style for textual publications.
Give dataset identifiers in the form of a URL wherever possible, unless otherwise directed.
Include data citations alongside those for textual publications. Some reference management packages now include support for datasets, which should make this easier.
Cite datasets at the finest-grained level available that meets your need. If that is not fine enough, provide details of the subset of data you are using at the point in the text where you make the citation.
If a dataset exists in several versions, be sure to cite the exact version you used.
When you publish a paper that cites a dataset, notify the repository that holds the dataset, so it can add a link from that dataset to your paper.