As professionals we use professional software, but we run into clients all the time who don't. Ever deal with a Microsoft Publisher file? Finally I found a solution to the file conversion nightmare. Zamzar allows you to upload files, then convert them to whatever format most fits your needs (pdf's in my case). It also does audio and video formats, although the file size is limited to 100mb (unless you want to sign up for an account). 

For more programs and tidbits we've found useful visit our resources page.