Update: This is an outdated post. If you’re looking for an ajax spreadsheet, Amit has a rundown of the new Google Spreadsheet and also lists some of the top ajax spreadsheets around the web.
If you take XML, Javascript, and the XMLHttpRequest object, then mix them up a bit, out comes an AJAX Application. The term AJAX has created quite a bit of buzz lately, I won’t try to explain the details (wrong person to do that ;-), however if you’re interested in reading more check out some of these tutorials and apps.
Now what does that have to do with Excel? Check out this Ajax Spreadsheet. It mimics the basic functionality of local spreadsheet, and even has some calculating fields (ie. if you change one cell, multiple dependent cells values will update).
And while you’re there, make sure to click and drag the column headings, very cool.
Also, it’s released with a GPL license. I’ve hacked together a local working copy for future experimentation.
Chris Kunicki posts about a new
Debra Dalgleish has an Excel site called 
So you’re building a spreadsheet that requires the user to enter a ZipCode, City, and State… How do you build a smarter spreadsheet that automatically fills in the City and State after the user inputs only the ZipCode?

I was just browsing the article 