Windows only: customise Google for IE doesn't offer all the myriad options of its Firefox progenitor, but Internet Explorer users still get more security and privacy, and less lock-in, from Google's products.
CustomizeGoogle's Firefox extension is a great tweaker for anyone who does serious Google searching—it was one of our must-have extensions back in 2006, and narrowly missed the cut for the 2009 edition. This Internet Explorer add-on doesn't offer nearly one-third, or maybe even one-quarter, of the sheer click-on/click-off options as the original, but that's not exactly a put-down.
Most of what customise Google for IE offers is pretty helpful. Gmail and Google Calendar can be forced to use secure (https) links, Google search pages can be stricken of those 18-mile-long click-tracking URLs you find when you try and copy them, and alternate links, like other search engines and Archive.org's WayBack Machine archives, can be tacked onto each page. Image searches can also point you right to the image, instead of the framed go-between page, and those with a mind for privacy can have their Google cookie anonymized and their Analytics reporting muffled.
Taken for what it is, customise Google for IE is a pretty helpful, and definitely useful inside its lightweight class. It's a free download for Internet Explorer on Windows systems only; it seemed to work fine on Internet Explorer 7 and 8, but let us know if you encounter difficulties in the comments.