There is very nice documentation of fread usage examples in https://github.com/Rdatatable/data.table/wiki/Convenience-features-of-fread
IMO this should be moved to proper package documentation (to be part of R package and not github project), ideally as vignette. We could have vignette on data IO (fread, fwrite) describing different options, optimizations (like #1656) and tricks like in linked wiki page.