There are several viable online spreadsheets -- Google and Zoho among the best known -- but there's a new player in town, and it has a compelling array of traditional spreadsheet tools plus sharing options.
SpreadsheetLIVE is a free cloud-based spreadsheet solution. You need to register to use the site, but you don't have to give away your real e-mail address. Once you're up and running, you can create spreadsheets from scratch or upload existing files from your PC.
There's a healthy array of features under the hood, including the ability to build charts and pivot tables. The interface is a bit bare-bones, though -- there are few Excel-like amenities like autosum, for example.
If you can get past that, you'll find all the formatting options you're likely to need. You can even insert comments in cells -- essential for collaborating with other users. And the site also offers a slew of pre-built templates for jobs as diverse as calendaring, leave form applications, and capital budgeting. Oddly, though, these templates are downloadable for Excel -- they don't work with the online SpreadsheetLIVE.
SpreadsheetLIVE give you all the most important bits of Excel in a browser, which can be a real lifesaver when you're on the go. Check it out. You might choose to bookmark this one permanently.