This Czech site (don’t worry, the link is for the English page) contains some useful software, routines, patches and fonts for AutoDesk related products. New uploads have their date highlighted in red so even if you check it once in a couple of months, it’s easy to see what’s changed.
Leonid Nemirovsky’s “Better than Nothing” routines are considerably better than most. He also has some tips and tutorials that you might find interesting. He has consistently updated them over the years.
It looks like the site doesn’t exist any more and, if it has moved, I cannot find where.
CadDepot also has a massive collection of blocks to insert into your drawings. Not all of them are freeware though and please look out for blocks that have been created by unlicensed versions of AutoCad. If you’ve ever had your drawings “infected” with the Educational Version watermark, you’ll know why this is important to check.
There are also lots of Fonts, font utilities and LISP routines so subscribing (free) to their newsletter will inform you of updates. You will need to sign up to access the files at this site anyway and it is well worth it in my opinion. They have never spammed me till date.
They also have a “make font” utility designed to aid in creating and customising SHX fonts. The program is designed so that anyone can customise fonts without having a thorough knowledge of shape files.