OptimalSort is a remote and unmoderated user research tool to help you understand how your users think about the content on your website or intranet using a technique called Card Sorting.
In traditional Card Sorting, you gave participants a stack of 3x5" index cards with example content on them and they sorted them into groups. After a number of people have done this you can collate the results and get some good ideas for designing a usable Information Architecture. Doing it in this manner was expensive, time consuming and thus usually only for very small studies. OptimalSort now allows you to do card sorting online which means you can invite lots more people and collating results is a lot faster.