I think keeping it in comments here is better since spreadsheets tend to to have a lot of messed up data (looking at previous surveys). What people share is definitely free-form, so I'd prefer to leave the data rather unstructured.
Creating a throwaway is also really easy and bogus comments are easier to deal with than someone messing with the spreadsheet.
I recommend making a web form using Google spreadsheets - which takes 3 minutes, and making the spreadsheet read-only.
When I last posted an open spreadsheet to hacker news it grew, then got defaced with all the data deleted. Someone restored it but it was work to ensure no data was lost.
However, I've created a spreadsheet (https://docs.google.com/spreadsheets/d/1MAIX9UEnpq0pAsMWr1NW...) if anyone prefers that.