I'm a big user of InputDirector, use to use Synergy.. now I'm a subscriber to Sharemouse.
Just a quick note on my thoughts here:
1. Free is great
2. Reliable is better
3. Supported is best
I've got nothing against opensource and sharing ideas, but a polished product is worth money, and one that has a road map and delivers on that roadmap, deserves a customer.
Sharemouse is a local lan KVM solution for [bi-directionally] sharing multiple keyboards and mice between multiple attached monitors. With a cut an paste buffer and cut and paste file transfer ability.
Its put out by the same people who offer MaxiVista, which is an IP monitor sharing tool for presentations and extending a desktop.
The licensing seems fair, free is two node and two monitor, standard includes additional nodes and features, professional offers the most nodes and unlimited attached monitors.
It is a lan solution, its not webtop sharing solution.
But it will also protect traffic with a shared password.
One of the coolest things is you can "donglize it" by putting your license key on a portable flash drive and there by "move" it from home to office and back and forth.
You can install sharemouse everywhere, only one device needs to hold a license, and only those nodes sharing a password can connect to each other.
It doesn't support Linux (sad) but Linux supports RDP so well these days if you need a desktop for a Linux server OS.. you can get that, but for the most part I use Linux as a server host and not a lot of GUI apps.
Drag and drop of files from windows to osx and back works, as does cut an paste of files.