Linking to other files, images, etc. in plain text or diary files

[RealityMonster]

Is there any way to include links to other objects in something like a
plain text or diary file?

Part of my work includes making a log of what I did that day, and I'd
like to occasionally reference things that I get in my mail like word
docs or image files. I did a cursory search on emacswiki, but this is
one of those things where you get a zillion hits because of words like
'image link text file'. :P

I've just been making my logs in diary files; is there a better way?
I've looked into planner a bit, but it seems a bit heavy for my
purposes.

Thanks,

JS