I think most everyone was a bit stumped by the question WillTell. (That still no excuse for over looking it - my apoligies - it is one of my pet peaves).
I also manage more domains than just about anyone I've ever heard of. How I deal with it all:
- run webserver on your local system for content generation and testing (a must). Setup your system as a perfect mirror of your online site - directories and everything - the whole 9 yards)
- templates. I use ssi based templates for everything. (one for page/html headers, one for top of page, one for bottom of page...menus and everything). To add content, it is just drop 5 standard ssi calls onto a page, throw on a title and some meta tags, and plop the content in the middle.
- I use a text editor that has "projects". The projects are just assorted collections of files that can all be loaded with a single click. If there are a 100 pages in this domain over here - no problem. Broad changes can be made with a single search and replace across all those files.
- The last real secret is a super fast ftp program called "leech". It is multi threaded and can download and upload up to 16 files (under 98) at the same time - what an enourmous time saver for uploading and downloading.
I've toyed with other systems like online cgi based html editors. Some are quite good and useful for frequently updated content. I use them in specific locations because they can't update a whole site very well.
I think the real thing you are after is a high quality editor that can handle multiple (dozens upon dozens) of files and run search and replaces across all of them. (UltraEdit, NoteTab, EditPlus)