Both Kindle and the iBookstore offer free samples.
They usually work really well though they do sometimes have problems, such as cutting off before the main text starts due to a long introduction. (And I downloaded a sample of the famously footnoted Infinite Jest from iBooks... didn't include any footnotes. Anybody know if that's just a limitation of the sample? My purchase decision depends on how easy it is to get to/back from the footnotes...)
They usually work really well though they do sometimes have problems, such as cutting off before the main text starts due to a long introduction. (And I downloaded a sample of the famously footnoted Infinite Jest from iBooks... didn't include any footnotes. Anybody know if that's just a limitation of the sample? My purchase decision depends on how easy it is to get to/back from the footnotes...)