Here at core, I use several freeware/open source tools and resources to make my life easier, and best of all, they are all free to use... A line-up :
This is currently (according to my opinion) simply the best RSS-reader available.
It is simple and works as expected with support for ATOM/RSS/RSS2.
If you need to track a lot of websites for updates, this is one of the most time saving assets you can have at this moment.
The blogging engine I am currently using (you are probably looking at it right now). Very versatile and easy to setup.
Simply the best FTP-client you can get
AntiVir Personal Edition
Free Anti virus that works (even the updates)
LavaSoft Ad-Aware Personal edition
Remove all trojans/dialers/unwanted stuff from your pc
Manage your photographs on your pc with a tool by google
An open source .NET IDE (no ASP.NET)
Visual C# Express Beta
A c# editor from Microsoft
Currently THE plug in for test driven development in .NET
The best embeddable scripting language. I still have to embed it myself, but that is another story ...
Create installation packages easily.
Demo tool for creating top of the notch graphical presentations. Quite complicated, but also very powerful. I need some more time to dive in to this...