PackETH is a nice gkt tool to play with Ethernet packet.
I encountered some path issues with the Makefile and openSUSE 11.1 64 bits to compile it, so here is the packETH-opensuse patch to compile correctly.
If you are on a 32 bits system, all you will have to do is editing the CPPFLAGS line and replace all lib64 occurences with lib.
I hope one will find it useful.