I'm taking user input (in a text box or whatever), and trying to make a file the user can then download.  What is the best way of managing the newly created files?

Should I assign them a unique name, based on a hash or something?  Or is there a way to preserve filenames without risking accidental name collision?

I really don't want a bunch of files to be created and slowly take up a huge amount of memory -- what's the best way of managing and purging temporary downloadable files?

(I'm trying to make something based of off Javascript and Python).

You might want to make a script that output the file you're generating without putting it in a temp file on disk (with print or something instead of the function you use to write to a file, I don't really know Python). You can then specify the MIME type and the filename with appropriate HTTP headers.