There's an even easier way to WOL that involves DynDNS (or memorising your current IP at least) and setting up some scripts within a DD-WRT flashed router. Then sites like
wakeonlan.me actually do WOW (Wake On LAN via WAN) correctly. For more information,
have a look here.
I use this method and it's faster than logging into the web GUI or telnetting the router and inputting command line stuff, and has allowed me to create a simple batch script which WOW's one of my home computers, allows time for it to boot or wake from sleep then connects to the VNC server.