Remote Support Toolkit.
Here is my Toolkit this is primarily all we do:
First off Picking the right Remote Support Client Makes all the Difference when it comes to background support Meaning (Un logged in/Late night Repairs)
I like in no particular order
UltraVNC
Logmein Rescue / IT Reach
and
NTR
They all have their Positives and negatives try to find one that has the ability to boot to safemode with Networking.
After you have your remote Support Client
The Tools:
First and Most important Tool in my arsenal isn't really a tool at all.
Many times we have to do research to solve a problem and from a customers point of view they see their computer just sitting their doing nothing the entire time they are watching the clock because they are paying by the hour/minute.
So in our case we have a simple Application that runs on their desktop showing the status of what we are doing with a little animation.
ie. It says Researching problem.....
and we just change the status as we start to work on different aspects of the issue.
This has been a life saver when it comes to customer perspective.
That being said back to the list.
All the standard onsite Tools, such as Hijack this, Adaware, Spybot, etc...
some great batch scripts can be found here.
http://www.microsoft.com/technet/scriptcenter/default.mspx
Another Great Tool we use for scripting is Autoit
http://www.autoitscript.com/autoit3/
Another tool we use often when time isn't crunched is
Microsofts unsupported virtual CD-ROM program.
With a little work you can setup a Remote Connection to your ISO'd CDRom Library and use that guy to load up and CD's that you may need on their Computer. keep in mind though unless it's on a LAN it tends to go Pretty Slow.
Another Great Tool to have in your arsenal is Thinstall, (however it is pricey, Real pricey but if you can afford it well worth the money.) Thinstall lets you do Full installs of Applications and then use them without leaving a fingerprint on their pc's and packages it all into a single package.
This last one takes alot of work before the issue occurs but it has been a life saver from time to time, and that is You can setup on Per PC Basis, a bootable Windows PE Environment which then can load up your Remote Support Software, which then starts up a Vmware Player Console allowing you to trouble shoot Bootup Issues Remotely. THIS is very slow, but when in a pinch its really nice to have.
And last but by far the most important tool I think is some sort of calling card software, So if they ever have issues in the future you can tell them to simply double click an icon and it will connect or email or contact you in some way and helps keep your customers for life.