3) Small admin area where you can monitor the urls being re-directed, the amount of times they have been re-directed and you can also delete urls that are not active.
4) Can be easily edited to fit into any design (template based).
5) Takes up little server resources
6) Can provide good advertising revenue, as you can display ads by loading the ads in the footer frame of the site being re-directed (config.php file has this setting available) or you can disable this to allow the re-direct go directly to the page.
7) Instant Download upon payment completion via Paypal or 2Checkout
PHP 4.0 or above
Apache Linux Server with Mod/Rewrite capabilities
I've updated (www.urlrely.com) to show the footer ads, using google adsense as an example, but it can be anything you wish as it runs off an ad.php footer file that you can edit however you wish. The colors etc, anything can be changed and edited in pure html/php.