Special notice! While MC Tween is a nice extension and it will continue to work for AS1 and AS2 until the end of time, it is my duty to inform all citizens that I have switched the focus from further development on MC Tween to a new AS2 and AS3 extension, a real Class this time, called "caurina.transitions.Tweener" (or just Tweener). Tweener doesn't have as many features as MC Tween yet (for example, it doesn't have native filter tweens), and the documentation isn't 100% done, but it features a complete, more solid redesign with a few additional syntax features that were impossible to achieve with MC Tween. And it works the same for AS2 (including Flash Lite 2+) and AS3.
So, if you use MC Tween, or you're thinking about using it, I'd like to suggest you try Tweener instead. It follows all the principles of simplicity I tried to feature on MC Tween, but with a more powerful syntax. Tweener download, examples and documentation are available on Tweener's page. You can read more about this change on this blog post.
Thank you for your attention and sorry for this ugly box. And don't worry, this website will not be deleted or anything.
Notice for October 2008: also note that, if you are still interested in MC Tween and don't want to use class-based AS2 or AS3 solutions, Larry Benedict has taken the matter into his hands and updated MC Tween with some filter features that are not available in the latest version. You can read more about it (and download his version) here or here.
Some links worth mentioning. If you see your link here when you have never mentioned it to me, hey, it's my Big-Brotherism acting. Send me mail if you think there's something that should be added or removed from here.
MC Tween related links
MC Tween @ proto.layer51.com - The original repository for this prototype, contains some great discussion (via comments) on MC Tween and its history.
Mandatory ActionScript library for animation - MC Tween - An introduction on why and how to use MC Tween, by Julian Pscheid.
Creating a Simple Button Effect Using the MC Tween Prototypes @ phireworx.com - An easy tutorial teaching how to create a nice button animation using MC Tween.
Simulando el scroll del navegador con flash - A tutorial on simulating the browser scroll with flash, optionally using MC Tween for scrolling. In spanish.
Done-with-MC Tween sites
Grafikonstruct - Well, all of the websites done at my old workplace are fundamentally MC Tween-based. There are way too many websites to link here, really, so check out the company portfolio and the news.
Joe Kid on a Stingray - Website for "Joe Kid on a Stingray: The History of BMX", a DVD telling the history of BMX racing (Nov/2006).
www.jeffguthrie.com - Website for Jeff Guthrie (Nov/2006).
low.style v 08 | a visual something - Nice and easy portfolio/personal website for Alex, from Germany.
Tween-extensions related links
Robert Penner - Of course, Robert Penner was the guy who created the easing equations used in this and on (all?) other tweening extensions. He also has a powerful and more OOP-strict Tween class available on his book. The father of mathematics on Actionscript.
Laco tweening prototypes - Another good tweening prototype, originally born as an AS2 version of my MC Tween but later evolved into something more. Also has some tweening benchmarks available (the MC Tween version used there is out-of-date though), as well as links to many other tweening extensions.
The Fuse Kit - A continuation of Laco's tweening prototypes, this is new approach to AS2 tweening with a component. Created by Moses Gunesch.
Tatsuo Kato's dynTween - Probably the first tweening extension I've seen apart from mine; uses a different timeline-like parameter concept which might prove helpful in many situations.
Flash MX 2004 Easing Classes - For the OOP purists, Macromedia Flash MX 2004 already comes with a bunch of easing classes, based on Robert Penner's equations as well. This tutorial by Devon Wolfgang teaches how to use them, with lots of examples. Worth a read.
Using the Tween and Transition Classes in Flash MX 2004 - Another article on using Macromedia Flash MX 2004's built-in tweening classes.
Protoypes/Actionscript related links
proto.layer51.com - The best source to find prototypes to automate common functions in actionscript. An invaluable resource for actionscript programmers that don't want to reinvent the wheel.
chattyfig.figleaf.com - Home of FlashCoders, simply the best actionscript discussion list out there. I've learnt a lot just by lurking on this list.