Hi,
In this post, I will be listing websites, which will help you with HTML, Javascript, Flash and others.
HTML
http://www.w3schools.com/
This website is one of the most popular to visit if you need help with HTML, I highly recommend this website.
http://www.bravenet.com/
This is another popular sites for HTML Codes. There many features on this website, which you can use.
http://www.htmlcodetutorial.com/
This website offers HTML codes for people who aren't quite familiar with making websites.
http://www.webmonkey.com/
This website is a bit more advance and it goes into depth a bit more than the others.
Flash
http://www.flashkit.com
Flash Kit offers very good tutorials on how to use flash. This webiste also offers Flash Codes for your own use.
http://www.flashadvisor.com/forum/
This forum allows members who are'nt quite into Flash, to ask questions, ask for codes and any other things which are related to flash. It also has a section for Javascript, DHTML and HTML.
http://www.flashvalley.co.uk/
This website is quite good in giving out flash game codes, flash components, flash tutorials and flash templates.
http://www.freeflashintros.com/
This website allows you to make your own flash chatrooms, guestbooks, poll, games and even more!
Javascript
http://www.javafile.com/
Visit Javafile for FREE Java Scripts and Java Applets on the Net.
http://www.javascript.com/
Another resource for free Java Scripts.
http://javascript.internet.com/
I would recommend this website, as its very easy to navigate and the Javascripts are excellent.
http://www.javascriptkit.com/
Anther fantastic site for scripts. If you need more help, then this site does have a forum.
http://www.echoecho.com/javascript.htm
Its layed out very well, and its very easy to navigate. Plus all scripts are free!
DHTML
http://www.dynamicdrive.com/
Again, this is a popular site for DHTML Scripts. Its very good at helping people who have'nt used DHTML.
http://www.dhtmlcentral.com/
This site has its own forum, tutorials and its own projects.
http://www.dhtmlshock.com/
Very good resource for DHTML Scripts and Articles relating to DHTML.
http://simplythebest.net/scripts/DHTML_scripts/
This site has a few DHTML scripts for you to use.
Sorry about the post being so big lol but I do hope this helps people.
Thank you once again.

PS: If you have any other sites, then do reply and I will add them to the list.