basically remote support apps.  

For the past year or so ive been installing TightVNC on machines i build, and many that i just look after.  I just want to know what other people use, ive played around with RealVNC and im not overly impressed, and Unicenter Remote COntrol from CA is far too expensive for me!

I use TightVNC with Hamachi.
Hamachi provides a P2P VPN of sorts and means that there is no direct Internet-VNC port mapping required.

I quite like LogMeIn too but that is quite expensive if you need to support a lot of machines.

If you have the ability to setup port mappings on the machines/routers then I have also found that remote assistance actually works quite well !!

We use UltraVNC at work.