Some tips when e-mailing representatives:
Some general information on keeping tabs on government can be found at this Citizen Journalist's Guide to Open Government.
This website/tool (a play on the Latin phrase Vox Populi, or "Voice of the People") provides information on current bills and how they are faring in Congress. Some of their apps make it easy to contact your legislators in support or opposition to bills being considered:
If you need to find out who represents you, check out one or more of these tools: