win2vnc lets you “use two screens on two different computers as if they were connected to the same computer.” I use this for controlling my laptop from my desktop’s keyboard and mouse. Very cool.
Unfortunately, it doesn’t support scroll-wheel events and some strange focus issues occur when special keys are pressed (Start, Alt-Tab, etc). I was going to offer a $40 Amazon gift certificate for someone to add support for capturing those events and sending them to the VNC Server, but it turns out that someone already released a patched version. It doesn’t quite work on my XP Pro machines — scroll events are sent, but special keys are captured by the “client”, albeit with less focus weirdness.
So, I’ll fork over a $40 Amazon gift certificate to someone that provides a working patch for the patch.

This is a very handy utility, but the lack of ALT-TAB and support for side mouse buttons or X-buttons is annoying. I’ll add $20 to that gift certificate if someone can figure out how to get the fourth and fifth mouse buttons to work on the server. I can probably figure it out, but I know there’s someone out there who can do it MUCH faster.
Go to the website with the patched version and look up the email address of that author. Send a full problem description and you might get a fix for free.
Let’s not cloud the issue with logic!
I assume the patched version you mentioned is the one at http://www.deboer.gmxhome.de/?
If so, try hitting Scroll lock. That takes care of at least alt+tab and ctrl+shift+esc. Ctrl+alt+delete is still captured by the client though, but I guess that’s hard to fix.
Why this isn’t mentioned in the documentation is somewhat of a mystery, I had to contact the person who made the patched version to find out about it myself.
Actually, it is mentioned in the documentation now. It wasn’t before though.
Feico told me about Scroll Lock in an e-mail and I never got around to updating the post.