I'm not a software developer but on occasion I've managed to develop a damned fine pimple   :P
I'm not a typist either.. :tellme: Two fingered hunt and peck so I have the other eight fingers held in reserve for picking pimples. :P

It's been almost six hours since I installed this on Win7/32 and I'm finally getting some action on .htm files, the first extension I assigned a handler to, using the File Association Manager. I think I'll leave that machine on all night since there's six partitions on a two terabyte drive, although there's little on the last four partitions except O/S type ISOs.
I'll keep you updated as I discover additional info.  :D

Tom,
I would be happy to do a mini-review but doubt that I can add much to the information and instructions provided in the original page from Vic Laurie above. He supplies a couple of links with instructions and screenshots from Codeplex that explains as well as I could on the procedure to follow to make it work.
My biggest complaint is the waiting.... :-[
I loaded the File Association Manager on a Win32 machine about an hour and a half ago. I selected .htm and .html to add a handler to. So far I found one html page where the "Tag" detail in the Properties sheet is active. and.... it's stated somewhere in the instructions provided that the "hotspot" to edit a "Tag" in a Properties sheet is near the middle of the line. If you click on the word Tag or near the left side, it won't open the editable link.
So.......... load the File Association Manager, select a couple of file extensions such as htm and html, following the instructions provided by Codeplex, and go fishing or take a long weekend  :D
That File Association Manager has to parse or index all the Property sheets on the machine so the time it takes will depend on the speed of the machine, the number of files with the extensions you selected, whether you shut down your machine at night (I did!), etc.
Select a couple of file extensions in the manager to start with. Go back tomorrow and add more if you want.... 8)
The extensions you use are the root types at the bottom of that list. Highlight the extension, then click on Add File Meta Handler and you are done. the rest remains Default ;)
The biggest bitch is waiting for the thing to parse half a million property sheets for each extension  :P
If this doesn't work using their instructions or something you don't understand I will come up with an Off again, On again, Gone again, Finnegan type checklist.
It's worth some time and effort so give it a go  :D