Like Google Wave, Google has not devoted much resource to their desktop search offering. While the counter-offering from Microsoft’s offering is not great, it is a service that is embedded into the operating system. (Windows Vista, Windows 7) Every time you hit the START button and type in the “start search” text box, it uses the search (and related indexing) services to find files, look up browsing history (Internet Explorer only of course), searching through your scribbles in Office OneNote notebooks.
If you installed Microsoft Office 2007, the program adds the corresponding iFilter to the service. If you install Adobe Acrobat Reader, the program adds the PDF iFilter so PDF contents can be searched. Different iFilters are used for indexing different file types.
Here are the file type and links to the iFilter I find by googling around. I would have prefer to add some additional ones (PNG, TIFF, and 7z) so searches in Windows for them can be better, but no luck. For more information on iFilters, see the Wikipedia article.
PDF (from Foxit): http://www.foxitsoftware.com/pdf/ifilter/
JPEG (AimingTech): http://www.brothersoft.com/jpeg-ifilter-40484.html
MP3/WMA/WMV (AimingTech): http://www.download3000.com/download-audio-video-ifilter-count-reg-27362.html
ZIP (Citeknet): http://www.citeknet.com/Products/IFilters/ZIPIFilter/tabid/69/Default.aspx
RAR (Citeknet): http://www.citeknet.com/Products/IFilters/RARIFilter/tabid/68/Default.aspx
To check whether you already have an iFilter installed for the particular file type, on the Windows Vista system, you can hit the start button, search for “Indexing Options,” and select that.
Then, click the Advanced button and grant permission to continue.
Then, select the File Types tab, and see what filter is used. As you can see from the picture below, for the PDF files on my computer, I now use the Foxit PDF iFilter.
UPDATED on December 7, 2011….
Some additional iFilter packs I find recently:
Microsoft office 2010 Filter Packs: https://www.microsoft.com/download/en/details.aspx?id=17062
Adobe PDF iFilter 9 for 64-bit platforms: https://www.adobe.com/support/downloads/detail.jsp?ftpID=4025