When researching, particularly collaborating, how often do you find yourself wanting to communicate some mathematics to someone who's not in the same room as you? Can you really be bothered to go into LaTeX, create a new document, type out everything in there, compile it, attach it to the email and send it to that person? What a pain!
This was the conclusion that I came to, and so I built myself a solution. ConTeXi is an add-on for Microsoft Office. Originally intended for Mircrosoft Outlook, it now also supports Word and Powerpoint. Just write your normal document, for example an email, and whenever you want to insert an equation, just use LaTeX, enclosing it in the normal begin equation commands. When you've finished writing (or at any intermediate point), a single click of a button converts your LaTeX into embedded images. This means that when you send your email, the recepient can see everything no problem. They don't have to install any special software, or have any special fonts available.
If you make a mistake, don't worry, you can convert the image back into LaTeX and edit it again. Variable font sizes and colours are supported as best as possible. In Outlook and Word, equation numbering and referencing is also possible.
ConTeXi grew out of my personal need for this tool, and I can assure you that it's already saved me loads of time! So, maybe it's also useful to you. For that reason, I'm making the software available as freeware, for immediate download. All you have to do is give me a valid email address. I promise that I won't spam you. If you find the software useful, I would appreciate a small financial donation.
System Requirements: This is a program for Windows. It's been tested on XP, Vista and Windows 7. You will need to already have Microsoft Office installed, either 2007 or 2010. I wouldn't expect it to work for earlier versions. You also need to have a LaTeX compiler. I use MiKTeX. In principle, other tools may work, but you'll probably need further help in getting it set up.