I use DropBox
....it has a "Public" folder that you can put files in and share with whoever you please. Once you place a file in the "Public" folder, you right click that file and choose Dropbox > Copy public link, then paste that link into an email or whatever and the file is shared. It is all stored on a secure server, so your computer doesn't need to be on for people to access the file(s).
And the files size can be in GB's not just MB's! You get 2GB of space free! If you want or need more, you can get 50GB for $9.99/mo or 100GB for $19.99/mo.
I started using Dropbox before we left on vacation in early February so that I could have easy access to some documents and pix and stuff while I was away. It can be easily accessed from my iPhone (there's an app for that). It was especially handy for keeping track of hotel reservations and confirmation #'s, as well as my maps with our planned stops, directions, mileposts, and stuff marked up on them.
You can access it from any computer that has an internet connection or through iPhones. And you can place files in it from any internet connected computer (or iPhone). It's been very handy for me, and I use it a lot!
I used it this morning at our local Jr. College. We went to an all day garden seminar, and in the hustle 'n' bustle of getting ready to leave home, I forgot our registration confirmation papers. HOWEVER
....I had placed PDF copies of them in Dropbox the day I registered. So I just accessed those files on my iPhone, and we were in like Flint!