Is there a Synergy-like application that only shares the keyboard?

Question

Basically, I don't need the "shared mouse" that Synergy has. I have a Macbook Pro with an external keyboard hooked up and a Windows 7 PC I'd like to share the keyboard with. What I'd like to do is just press a key to toggle which computer the keyboard is hooked up to. Essentially, what I'm looking for is a "software KVM," minus the video and the mouse parts.

I thought I could just use Synergy, disable the "links" that allow the mouse to go from one screen to another, and use a key combination instead, but then any mouse input, including the internal trackpad, will still be redirected to the client when the client screen is switched to with the key combination. What I want is to be able to still use the internal trackpad and keyboard in my Macbook Pro, while still sharing the external keyboard to the Windows PC.

Alternatively, if no such application exists, if someone could comment with what the best cheap USB KVM (or only keyboard/mouse) switcher is, I'd appreciate it :)