Here's something I put together about 2 years ago but never took to production. It's called the CarNetix CNX-PWOL and is designed to wake a sleeping laptop by exercising the Wake-on-Link feature that *some* ethernet chipsets implement. The problem we ran into was, very few laptops seemed to have the Wake-on-Link feature (many have the Wake-on-Lan "majic packet" feature, but not Wake-on-Link). The link above tells you where to look for the feature in your laptop.
I'd love to hear from you guys on how many of you have laptops that include Wake-on-Link. If there is enough interest we may resurrect this project.
Here are a couple of photos with the CNX-PWOL prototype. It includes an RJ-45 input, RJ-45 outout (pass through), an ACPI input, and a battery input to run a small relay. It is shown here with the P2140 and PSUmoni software on an IBM laptop. The PSUmoni issues a "hibernate" command to the laptop via the USB connection to put the laptop into sleep mode. The PWOL shorts two pins on the RJ-45 to wake the laptop.
There's another possible "non-solder" solution for laptop users. Take a look at this thread and let me know if your laptop has this feature (mine does not).
Let me know what you think.