The Mission Cards can be used without the Meeting Engagement rules - simply deal 1 card to each player at the start of any scenario. If the card's mission is strictly impossible to achieve, reveal the card and choose another at random.
These are the rules for the Meeting Engagement scenario, and the rules for using Mission cards in both regular and Meeting Engagement scenarios: 
Here are the cards:   
Here are the card backs:
 

Here are the pdfs:

 Here's an example page from an earlier version of the Objective Cards to which another fan added beautiful graphics: 

Western Front 1: 
Western front 2: Box1
 
Eastern Front:


North Africa 1:


North Africa 2:

Box2 (above)

Italy:

Here's a simple campaign idea for Eastern Front scenarios both official and user: 

An old M44 fansite of mine: http://www.freewebs.com/yangtze2000/index.htm
Brycie's fansite: http://www.freewebs.com/brycie35/campaignmaps.htm
Brummbar's fansite:http://www.brummbar44.com/
Memoir at BGG: www.boardgamegeek.com/game/10630

This document lists official scenarios in order of play balance, giving you a handicap figure for one-off games. It probably needs updating in the light of latest figures, but it's still useful as a guide:
 

Experimental Rules - work in progress.

Weather Rules