Google Spreadsheets
Inevitably, Google enters the online spreadsheet market to provide competition for ThinkFree. No charts (yet) and limited invite only but it's coming.
As an aside, I don't use Excel much. My kids are much more proficient at producing pretty, colourful pie charts and histograms than me.
However, I also find it quite staggering that many sensible, intelligent adults spend their lives in Microsoft Excel. A gentleman once emailed me a spreadsheet and I hunted high and low across all tabs for any relevant table data, pretty charts and forumlae.
Finally, I had to admit defeat and called him rather sheepishly. It turned out the 'data' was simply plain, good, old fashioned text (words) in various cells (paragraphs).