If you use Google Docs more than you use Microsoft Office, you'll be happy to know that they added support for 12 new file formats, including Excel, Powerpoint and Photoshop files. Here's the full list:

Microsoft Excel (.XLS and .XLSX)
Microsoft PowerPoint 2007 / 2010 (.PPTX)
Apple Pages (.PAGES)
Adobe Illustrator (.AI)
Adobe Photoshop (.PSD)
Autodesk AutoCad (.DXF)
Scalable Vector Graphics (.SVG)
PostScript (.EPS, .PS)
TrueType (.TTF)
XML Paper Specification (.XPS)

[Google]