The only limit that we’ve had up until recently was that if you wanted to create interactive content you needed a client application running on your local machine. To create Flash you needed to purchase, install and use the editing tools locally. Which brings me to the point of this post. I only recently found out about a new crop of web based IDEs (Integrated Development Environment). In no particular order.
You can create and edit .Net , Silverlight and many other types of projects. This is the best damn thing ever. I hope someone at Microsoft buys these guys.
All your stand website editing power with Git and Mercurial integration. Paid accounts offer many must have features but the free version can get you up and running quickly.
Now for the design side of things
It’s not nearly as new but the design side has been very well covered too.
The current leader in desktop design has an excellent head start on the web with their Photoshop.com service
Aviary is quickly becoming a designers hub online. What started as a Photoshop lite application for minor photo tweaks has quickly evolved in to one of the best collections of creative applications that run in the browser.
My personal favorite web based photo editing tool. I became hooked on Picnik thanks to its early Flickr integration that made it so easy to jump right in and edit my photos already on Flickr.