According to Perlman (2009), "Questionnaires have long been used to evaluate user interfaces (Root & Draper, 1983). Questionnaires have also long been used in electronic form (Perlman, 1985). For a handful of questionnaires specifically designed to assess aspects of usability, the validity and/or reliability have been established, including some in the [table below]."
This wiki has a list of generic usability survey instruments that can be adapted to specific websites. Often, it is good enough to replace the word "system" by "web site". There are more than 15 questionnaires listed here.