Yep, dropbox is great. Just keep in mind that there are limits to how much you can upload (I think it's 2GB for a free account, so it will hold quite a few maps), so it's good to at least have a low-res version on the forum as Gidde said, and then you can link to a hi-res version on dropbox. That way if you ever need to clean out your public dropbox folder, at least there is still something on the page here to look at - you know, for posterity or whatever.