When designing with photographs, or making exhibition graphics and banners, or sending a film to a competition, the large files involved can clog up email. This makes it difficult to share work with clients and printers.
So some time ago I discovered MailBigFile. Its cheap and easy to use and it has always worked. You just put in the email address to send to, browse to your Big File and go. It can take a while to upload but you can just carry on with other work or have a coffee while its sending. The recipient then gets an email inviting them to download the file. You can get an alert to see when they have downloaded the file.
There are other services like this too but I do like this one for its very simple process.