Google Spreadsheets, not yet launched by Google, doesn't intend to compete with Microsoft Excel because it will have only basic capabilities. If you're wondering how would use Google Spreadsheets, here are two salient opinions from Digg.
"I have a very good use for it. Every year, I manage a small vacation for me and around 20 friends. We rent a beach house for a week or two and just generally have a good time. However, because people can't all be there on the same day and so forth, there's always a bit of disagreement over how to split the cost of renting the house.
So I created a spreadsheet to track this sort of thing. It basically splits the number of nights everybody stays up and with that and the total rent costs and some minor math, it works out a cost per night for everybody. Stops any disagreements dead.
The only problem is that sharing it is kind of a pain in the ass. Having it online like this and accessible to those people only, that would be just excellent. If it's editable (and the editing capabilities are able to be limited), then I can have people put in their own dates and show them the results in real time. It would be very handy. If I could integrate it with a webpage to gather all our data into one location, well, that would be the best thing ever." (Otto)
"Some of you are putting way too much thought into this. Google Spreadsheets isn't meant to replace Excel. It's definitely not for power users that require complex macros or equations. And it's definitely not for people that need a mission critical spreadsheet application. This is a simple spreadsheet app for simple usage. From my observations, the casual Excel user mainly uses spreadsheets to create lists in tabular form, or they use it to create a simple personal budget. This is the target audience for Google Spreadsheets.
Take another look at the screenshot. The sample spreadsheet they show is a game schedule for a little league team. See what I mean? For people that don't need the full power and capabilities of Excel, Google is offering a simple and free alternative.
I'm still going to use Excel for work related stuff. But for personal stuff, I'm going to use Google Spreadsheets. I can access it just about anywhere and I can display/share spreadsheets with family and friends. Still not sure what to use it for? Here are some ideas..
* Catalog and share your music and movie collection
* Record your car gas mileage/usage
* Track your daily spending
* Keep a training journal for how many miles you walked/jogged/cycled
* Track the money you've raised for your charity or fundraiser event
* Make a note of how many times your boss uses the word synergy." (RegisteredUser)