Merging PDFs (and other useful tasks)

If you need to merge two pdfs, as for example, when attaching forms 9 and 20 to the thesis manuscript, pdftk can be useful. Free, portable across platforms, and without the need of administrative privileges, it does a lot of useful things. From the creators: "If PDF is electronic paper, then pdftk is an electronic staple-remover, hole-punch, binder, secret-decoder-ring, and X-Ray-glasses." Can be downloaded from http://www.accesspdf.com/pdftk/.