• this site has Ajax code (that only works with Firefox/Netscape) but also the PHP receptor script
• this page had a short and sweet code snippet showing you how to do the basic file upload with php
• this page from ppk has a great tip on making your input boxes for file upload look stylish
• According to this page:
  "there are generally limits on the quantity of data that can be sent in any one request — for example, PHP has a default limit of 2MB (although this can be changed, using ini_set(’upload_max_filesize’, ‘[new size]M’) where new size is the maximum number in megabytes — this will not work if safe mode is enabled on your host).

-- MattWalsh - 31 Aug 2006