Found super fast tools to divide A4 to 2 A5 pages
 

After google a lot, I find super fast tool to cut A4 pdf into double pages A5 file.

I did one, and attach it behide, you guys can check it out.

Using DOS command to do it, and it done very fast, I split the 210K size pdf in 2 seconds, and the outcome file is 240K only, very effective!

You can find the software here:
http://www.rubypdf.com/

There are two softwares needed: PDFRotate and PDFDivide

First copy all software and the PDFs into one directory, the 2 simple steps:
1.First use PDFRoate
\PDFRoate 1-A4.pdf 1-A4-90.pdf 90
Rotate pdf 90 degree first, prepare to divide it.
2.USE PDFDivide
\Divide 1-A4-90.PDF 1-2A5.PDF

The only none-beatiful thing is that it cut directly, so in some pages there are 1 line letters been cut into 2 parts.

But anyway, it's nice and fast.

I like this idea of splitting and had tried batch splitting using photoshop macros. My ony reservation for splitting pdf is that the speed of turning pdf pages on sony reader is too slow compared with the speed of turning lrf or rtf pages. So now I am following the developments of PDFread and Rasterfarian, both of which can process large pdf pages into smaller lrf pages for quick page-turning on the reader.

Th best tool for your scope is "JEP" (Just another printer.
You can select the zone you want to crop in pages.
You can divide a page in 2 or 4 parts.

You can download it here

Bye

Thanks!
JeP is a great ebook tools :)