Our system will handle up to 100 Free Checkouts per day for you, but you don't actually need any special "download service" like E-junkie if you aren't selling your download and don't need to restrict access to paying buyers only.
If you just want people to download a file for free and don't need to issue each person a unique link that expires, then you can just upload the file to your Web site and make a link to it, just like you'd make a link from one page to another:
<a href="http://www.yoursite.com/path/to/yourfile.ext">Click here to download my file</a>
If you at least want to collect names/emails, but you still don't need to issue each person a unique link that expires, you could have a generic HTML contact form on your site that submits to any generic form-handler script, or even a subscription form for a mailing-list service like Aweber, which then leads to your free-download page after the form is submitted.