There's at least one guy running around with something like that already. He's using a semi-transparent display in front of one of his eyes, and it augments the image of e.g. the building he's looking at with additional info. There's a web page somewhere with illustrations, but it's been so long since I looked at it that I've lost it in the overflowing list of bookmarks.

And, as he said in an interview, he's online as well, so when he's in the shop his wife would frequently send shopping lists to his little eye-display..