Your online media kit should include the same elements as your printed kit. Before you build it, think about what you want to accomplish. Your Number One goal should be to include anything that will make a journalist's job easier and faster. The kit can include the following:

Company history
Bios and photos of key executives
Facts about the company
Lots of free information, including articles and speeches written by company executives
The latest news releases. Include the PR contact's name and phone number on each release
A list of your products and services, with product photos
A Q&A sheet
Links to related sites
Reprints of articles written about you
A list of media outlets that already have covered you. This should include TV and radio shows where you have appeared as a guest

Don't worry if you can provide only some of the items on that list. Remember that journalists are usually on deadline. They shouldn't have to wade through mountains of information to find what they are looking for.
To learn more about how to create an effective, usable, and downright awesome online media kit, see Special Report #22 "How to Create an Online Media Room and Keep the Media Coming Back"