SuperKids Parent, Teacher, Student Guide to Impeachment -- No commentary, just the facts about the law, the process, and the history of Impeachment.
The US Constitution -- Neat! Use your browser's "find" button to search for words like "impeach."
Jurist: The Law Professors network -- Enough information for a law professor!
Procedural Process for Impeachment and Censure Resolutions -- Selected articles in CSPAN.
Impeachment Process bibliography -- Non-web resources.