Release/file sharing service At my company we use FTP to share releases and e-mail to notify customers of the availability.

I'm looking for a service offering:


Easily upload of a file
Users need to sign in to download 


and keep a record of which user have downloaded what

proper UI


Any ideas?
What you're after is an Binary repository manager

Quoting from Wikipedia with added links:


  Notable Universal package managers include:[6]
  
  
  Apache Archiva
  Jfrog's Artifactory 
  Inedo's ProGet 
  Sonatype Nexus
  


I know for sure Nexus and Artifactory match your requirements (even if proper UI is a bit subjective and you mileage may vary).