AUGI Autodesk User Group International, one of the most visited forums on all of AutoDesk's products. Chances are good that someone there might help you if you get stuck. Or simply if you want to find out if something can be done "better".
CadTutor This site also contains some useful tutorials. But mainly it's another forum where users help each other, some find it friendlier than AUGI. Also the site is totally independent of AutoDesk, you might even find someone able to help you in other CAD programs.
TheSwamp This site is arguably the best when you want some help on creating AutoLisp routines yourself. Many of the most experienced AutoLispers can be found roaming on these pages.
Cadalyst A site chock full of useful hints by one of the greats (R.K.McSwain) - you'll probably run into him on AUGI. You can also see his blog here.
Lee Mac - Tutorials Some helpfull tutorials in How-To work with lisp addons. If you have a lisp but don't know how to use it - these pages will help no end.
Google There are litterally hundreds of such sites. Some even provide free tutorials / videos.
Programming Resources
AfraLisp AfraLisp has been a staple resource for examples and tutorials for all that's AutoLisp ... for years now. Many would tell you to view these pages if you want to 'Lisp' for yourself.
Jeffry P Sanders Lots of samples here, good resource to learn from or just use as is. You can even ask for some help it seems.
Lee Mac - Programs Although Lee's not been in the Lisp scene for very long (only a few years), he's grasped the concepts very well. To the point where his examples are awesome resources for those wanting to learn, even those 'old-hands' wanting to find new ways of doing things.