I just created a Share This Topic Mod. You can find it at SnitzBitz by clicking here.
The purpose of this mod is to allow your users to share your topics to services such as Facebook, Twitter, StumbleUpon and many more via the www.addthis.com site.
This mod is VERY simple to install. You only need to upload one file and add one small bit of code to one file! Very easy!
Here is a screenshot of it:


When the link is clicked, the options are revealed:


In the above screenshot, when you click on More Options, even more services are available:

Very Cool, LeatherLips!
Many thanks!

Great mod LL! Sincere thanks Andy

Works great, and its so simple to add, all forums should have this.

I've updated it a bit to v1.1. The newer version is at SnitzBitz.
These are the changes:

• Fixed the placement of the code in topic.asp. In v1.0 the Share Topic links did not appear if the forum was set to not show the Printer Friendly link.
• The forum name is now visible in the pop up that is displayed when the More icon/link is clicked. It appears in the right hand corner.
• This version is much easier to customize which social sharing sites you want to show as the main choices. The default is Facebook, MySpace, Twitter and Email but can very easily be changed.

Here are the screenshots:


When the More icon/link is clicked, all of the options are revealed:

Niiiice! Perhaps I find the time to install this during the weekend.

This is interesting.
I always include sharing tools on my sites, but I have never used these tools on any site I visit and have never seen anyone use the tools on my sites. Has anyone had any success with sharing tools?

I don't know if they are used too much or not. I suppose some people use them. If it helps drive some traffic back to your site I guess it can be beneficial to have them.