I have (finally) found a way to open .mht files
I got the idea from this post
... and the recent release of Opera Mobile for Android (and it's Save As (might even be mht)
You need Opera Mobile. After you get it just access the file through the address bar.
Now that we have a browser that can actually open .mht files properly (Dolphin HD could open them but it did not display correctly) the question is how to make this to be a default action when selecting the file from your explorer of choice. (Typing it in the address bar each time is not a practical choice... although we coould probably make bookmarks for the opened .mht)
I have tried figuring out how to do on Android the equivalent of "file association" on Windows (or Linux). It seems it's not as straightforward as I'd hoped it would be. The only thing I've found related to it so far is the "Edit File Extensions" submenu in Astro File Manager's preferences. This looks like the thing that might (help) do the trick.
For all I know it might even be impossible if you don't have root access to your device.
If anyone knows more on the subject of Android's "file associations" or maybe happens to have a link to a good tutorial or forum discussion on this... please respond. I know this is not the topic of this thread but it is related.
P.S. As a possesor of already quite a large .mht collection (I use it to store random articles in a self contained format for later perusal) I would also like to see this problem solved.
P.P.S. I don't understand why Opera Mobile hasn't included an "Open" feature as it seems it renders .mht quite correctly.
have a good one...