When Google learned the NSA was intercepting traffic from its internal networks, the company's answer was simple: encrypt everything. And you should, too. Forcing websites to use encryption whenever possible—with browser plug-ins such as the Electronic Frontier Foundation’s HTTPS Everywhere, if need be—keeps no-goodniks from swiping your logins and personal information.
Don't stop at websites, though. If you carry personal data on a USB stick, encrypt it with Microsoft’s BitLocker to Go, or create encrypted file containers via the Disk Utility in Mac OS X. Open-source encryption options for Windows include FreeOTFE or DiskCryptor. Encrypt your external hard drives, too—especially your backups.