You can place that value in a cookie.
The complete list of alternatives is
- Standard HTTP cookies
- Local Shared Objects (Flash cookies)
- Silverlight Isolated Storage
- Storing cookies in RGB values of auto-generated, force-cached PNGs using HTML5 Canvas ag to read pixels (cookies) back out
- Storing cookies in Web history
- Storing cookies in HTTP ETags
- Storing cookies in Web cache
- window.name caching
- Internet Explorer userData storage
- HTML5 Session Storage
- HTML5 Local Storage
- HTML5 Global Storage
- HTML5 Database Storage via SQLite
Evercookie
