The Huffington Post Investigative Fund welcomes tips, links and newsworthy documents on stories of national import. If you are concerned about maintaining your anonymity, you may want to consider one of these options.

HIDE YOUR IP ADDRESS
TOR: http://www.torproject.org/
Download: http://www.torproject.org/download.html.en

Tor's free software allows users to hide their IP address among hundreds of thousands of IP addresses. The Electronic Frontier Foundation provides a great explanation of how it works:  Using Tor can help you anonymize web browsing and publishing, instant messaging, IRC, SSH, and many other applications. The information you transmit is safer when you use Tor, because communications are bounced around a distributed network of servers, called onion routers. This provides anonymity, since the computer you’re communicating with will never see your IP address — only the IP address of the last Tor router that your communications traveled through.

ENCRYPT YOUR E-MAIL
Hushmail: http://www.hushmail.com/
Sign up: https://www.hushmail.com/signup/

Hushmail provides standard encryption for its free, web-based e-mail accounts. Encrypted messages are only accessible to end-recipients with a proper key. For more on encryption and additional security resources, visit the Electronic Frontier Foundation's site: https://ssd.eff.org/