Many federal agencies, including NIH and NSF, now require grant applications to include data management or sharing plans for projects that involve the collection or creation of data. These data management plans, usually expected to be around two pages or less, typically include such areas as a description of the data and metadata to be used in the project, how these data will be stored, managed, shared, and preserved, and any associated legal or ethical issues.
Planning out the needs of the data to be included in or created by your project is a critical step. You need to outline what formats your data are in and how this data will be stored, backed up, and, if necessary, preserved for future use. Factors to consider are the storage space needed now and in the future (which can become substantial for image, GIS, and multimedia data or data collected through sensors) and restrictions on who can use and access the data.
It is important to consider the legal and ethical issues that can be related to your data, such as confidentiality, privacy, and intellectual property.
American University's Institutional Review Board (IRB) oversees research, which often includes data collection, involving human subjects; the IRB also has a policy regarding Research Involving Secondary (Existing) Data Sets.
An online guide about Responsible Conduct in Data Management, developed by Northern Illinois University, can be found on the web site of the U.S. Dept. of Health & Human Services, Office of Research Integrity. Seven topic areas are included: Overview of Data Management, Data Selection, Data Collection, Data Handling, Data Analysis, Data Publication and Reporting, and Data Ownership.
Sharing data that you create through a project funded by a federal agency is an important component of your data management plan. As stated within the NSF Data Sharing Policy:
"Investigators are expected to share with other researchers, at no more than incremental cost and within a reasonable time, the primary data, samples, physical collections and other supporting materials created or gathered in the course of work under NSF grants. Grantees are expected to encourage and facilitate such sharing." (http://www.nsf.gov/bfa/dias/policy/dmp.jsp)
You can share your data in a number of ways, including simple ones such as posting it online through a project or university website. Be aware, however, that this may not be a long-term archival solution - for example, of the website's existence is bound to the account of a particular project member, who might leave the university.
One of the most effective ways of sharing your data is depositing it into a known archive for your institution or discipline. American University Library has a Digital Repository that can be used by AU researchers to share their data, within certain technical restrictions.