Some interesting HTTP header fields from Wikipedia:
- If-Modified-Since — Caching
- If-Match — ETag (for a PUT?)
- If-None-Match — ETag, for caching
- Content-Disposition — For showing a “File Download” dialog box
- Content-MD5
- X-Frame-Options — “Clickjacking” protection
- X-Content-Type-Options — Tell IE not to ignore the declared content type