I recently noticed there were loads of broken links to our site for products that we have took off the site.
This mod will add an extra button into the "Status" column in the admin panel so you can now set an item as "Active", "Discontinued" or "Inactive". The new discontinued settings will stop products showing up on your site as if they were inactive, but allow people following a direct link to the product to view it and see that its discontinued. This way you will not lose out on any hits to your site, and can use cross selling to recommend alternative products.
The install instruction are quite long so wont post them again here. They can be found on the forum at http://www.oscmax.com/forums/custom-mods-hacks/28300-discontinued-products.html
Additionally I have attached files which have the mod pre-installed to my 2nd post in that topic. The files are from 2.5.1 so may cause problems if you just drop them into any other version.