This is a good and free webmasters tool, available since 2005. With Browsershots, you can see what visitors with different browsers view when they open your site. This will allow you to improve your site and have more visits.
Browsershots let you preview screenshots in several Linux, Windows and Mac OS browsers. There is a lot of browsers in different versions you can select: BonEcho, Dillo, Epiphany, Firebird, Firefox, Flock, Galeon, GranParadiso, Kazehakase, Konqueror, Minefield, Mozilla, MSIE, Navigator, Opera, Phoenix, Safari, SeaMonkey.
When you submit you will be redirected to a page where your site images will be uploaded. Just reload the page or bookmark it to go there later. In the end you can also download a zip file of your browsershots. This operation has a time limit that you can extend if you wish.
This is all free and the screenshots are made on distributed computers around the web that are run by volunteers. Screenshots that haven’t been accessed in ten days are deleted.