I have hosted the large image file on imgur. Its free and they allow you to do unlimited upload of png/jpeg files. You can sort them into albums. Etc. I think it is a very good free service. I use it to host my maps as well and also the above tutorial.
Here is the tutorial with a sort of slide show please check it out and give me some feedback.
http://imgur.com/a/EstMH#0
Also my maps so far I've completed 5 of them, they are huge, feel free to download the full resolution.
http://imgur.com/a/ssMsk#0
Also a link to that thread.
http://www.subsim.com/radioroom/showthread.php?t=213138