PDF Resize is a high performance server tool from Traction Software for Windows PC, Unix Aix, Linux, Macintosh OSX, HP-UX

PDF Resize software automates the process of resizing the pages of pdf`s to a new page size.
NOTE: This does not compress or loose information.
PDF Resize contains many special features like making all pages 200% larger, change x or y size of the page e.g. 200x150%, make all pages a certain size e.g. ALL A4 size, you can start from any page, 1 in nth pages, odd, even page sizing, constrain proportions when scaling to a odd size page and also can center on the page.

simple command line parameters:

e.g. PdfResize test.pdf out-test.pdf -scale200
will resize all pages x2 size. (200% bigger)
e.g. PdfResize test.pdf out-test.pdf -page A4
will resize all pages to A4 size (portrait)
e.g. PdfResize test.pdf out-test.pdf -pageL A4
will resize all pages to A4 size (landscape)
e.g. PdfResize test.pdf out-test.pdf -page A3 -con -center
will resize all pages to A3 size and constrain proportions & center on the page.
e.g. PdfResize test.pdf out-test.pdf -scale200 -s1,3-4,6
will resize pages 1, 3-4 & 6 x2 size. (200% bigger)
e.g. PdfResize test.pdf out-test.pdf -scalex200 -scaley150
will resize all pages x2 X size and 1.5 y size. (200%x150% bigger)
e.g. PdfResize test.pdf out-test.pdf -pagesize 0,0,1000,500
will resize all pages to a specific size, 1000x500 points

e.g. dir /B *.pdf > list.txt, then PdfResize list.txt -fout -scale200
list.txt file contains:-
in1.pdf
in2.pdf
in3.pdf