Sometimes it is hard to send large files to people using email as the recipient email account may limit filesize of an email attachment.
Recently I found out there is a service called SendThisFile which enable you to easily transfer large files to email.
When you register an account (there is a free plan) and send your file to a recipient, the file will be actually uploaded to their server and they will send the recipient an email with a link to the file. Then the recipient can click the URL to download the file. Free account do have some limitations but it does do the work pretty well.
Update: Some lifehack.org readers have suggested two more similar services called YouSendIt.com and DropLoad.com. Both are very good file sending services. Thanks Tomislav, Maneesh and Ryan!