And here's one more that's more easily navigable:
http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.html
A scripting way to find out for your current machine:
ls /usr/share/man/man2 | sed -e s/.2.gz//g | xargs man -s 2 -k | sort | grep -v 'unimplemented system calls'
Credit - http://www.cs.fsu.edu/~langley/current-system-calls.html