Those are some very pretty maps. Remind me of the old Final Liberation game. Oh Emperor, how I loved that one.
Arcsquad12: Nice - bigger and sharper version. Good find.
I also found another map in the Codex Planetstrike, but that one - whilst looking neat - doesn't have any military symbols...
If you don't like the ones from
GW (I have to say, I rather like the triangles

), perhaps Forgeworld's Imperial Armour books would have something? They often tell a story about some big military campaign, at times featuring cool maps.
Or how about just using a Mechanicus-style cog symbol for "valuable technical facility"?