<a href="http://homepages.ihug.com.au/~nemesis2k2/">Nemesis' Sonic hacking site</a> - Great site with great hacking guides by Nemesis.<br>
<a href="http://sonicology.fateback.com/">Sonicology</a> - Contains very good hacking guides by Hivebrain.
<a href="http://ssrg.shadowsoft-games.com/">SSRG</a> - This site will host your hack. It also has a hack archive.
<a href="http://projectnemesis.ibforums.com/esrael/">Esrael Sonic Hacking H. P.</a> - Esrael's hacking site. The site is in Portugese, but there are babelfished guides =P
<a href="http://www.shadowsoft-games.com/">Shadowsoft</a> - A hacking group that released many good quality hacks.