That's exactly the approach the unix tail command takes so it seems reasonable to assume there isn't a better way.

strace tail -2 xterm.faq.html
...
open("xterm.faq.html", O_RDONLY)        = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=257717, ...}) = 0
lseek(3, 0, SEEK_CUR)                   = 0
lseek(3, 0, SEEK_END)                   = 257717
lseek(3, 253952, SEEK_SET)              = 253952
read(3, "href=\"manpage/resize.ps\">ps</a>\n"..., 3765) = 3765
...
write(1, "</body>\n", 8</body>
)                = 8
write(1, "</html>\n", 8</html>
)                = 8
read(3, "", 0)                          = 0
close(3)                                = 0
...
[download]