No physical access needed, root access is sufficient.
No bootable floppy disk, bootable CD-ROM or other media needed.
No keyboard or monitor needed. Simply reflash remotely via SSH.
No instant reboot needed. Reflash your chip in a running system, verify it, be happy. The new firmware will be present next time you boot.
Crossflashing and hotflashing is possible as long as the flash chips are electrically and logically compatible (same protocol). Great for recovery.
Scriptability. Reflash a whole pool of identical machines at the same time from the command line. It is recommended to check flashrom output and error codes.
Speed. flashrom is often much faster than most vendor flash tools.
Portability. Supports DOS, Linux, FreeBSD, NetBSD, DragonFly BSD, Solaris, Mac OS X, and other Unix-like OSes. Partial Windows support is available, and full Windows support exists as a patch.
IMPORTANT: If something went wrong during flashing, do NOT turn off/reboot your computer. Instead, let us help you recover. We can be contacted via IRC (#flashrom on irc.freenode.net) or email. Please allow for a few hours until someone responds on IRC, we're all volunteers.