Web Development Tools
Weebly -- cloud-based web site development and hosting platform
Zoho Creator -- cloud-based development platform for database-driven web applications
HTML Editor -- interactive cloud-based HTML editor
CollabEdit -- syntax-highighting text editor for multiple programming languages
PasteBin -- another interactive cloud-based HTML paste bin
Picasion or WeGIF or MakeAGIF for creating animated GIFs
DaButton -- cloud-based button making tool
AddThis+ -- Social Networking Gadgets and Buttons
Screenr -- create screen casts
Cloud IDEs, Pastebins, and Editors
Cloud 9 -- HTML, CSS, PHP, Ruby, and JavaScript Cloud IDE
JEdit -- Cross-Platform Editor for JavaScript, HMTL, CSS, PHP, and more
Zoho Creator -- cloud-based development platform for database-driven web applications
HTML Editor -- interactive cloud-based HTML editor
CollabEdit -- syntax-highighting text editor for multiple programming languages
PasteBin -- another interactive cloud-based HTML paste bin
Picasion or WeGIF or MakeAGIF for creating animated GIFs
DaButton -- cloud-based button making tool
AddThis+ -- Social Networking Gadgets and Buttons
Screenr -- create screen casts
Cloud IDEs, Pastebins, and Editors
Cloud 9 -- HTML, CSS, PHP, Ruby, and JavaScript Cloud IDE
JEdit -- Cross-Platform Editor for JavaScript, HMTL, CSS, PHP, and more
Visual Modeling Tools
Financial Modeling Tools
Excel Live -- cloud-based version of Microsoft Excel
Google Sheet -- cloud-based spreadsheet tool
Google Sheet -- cloud-based spreadsheet tool
Wikis
The above tools are all cloud-based and are accessible through any browser that supports Flash and/or Java. Be sure to test them on mobile and ChromeOS devices. Unless indicated otherwise, the tools are free or an educational license has been obtained through a grant. Access the tools through the above links to obtain the free licenses.