Question for the book scanners

[Dave Britten]

I've got a few small books that I'm scanning by pressing them flat on my scanner. The results are pretty good, but of course I get two pages in a side-by-side format doing it this way. Are there any free/cheap tools that could largely automate the process of splitting the pages down the middle and turning them into two individual pages in the PDF? Ideally something that just lets me select a range of pages and click the "go for it" button.

I tried DeftPDF last night, and the results looked good, but it nearly doubled the size of the file. Upon closer inspection, all it did was duplicate the selected pages, and then crop them to either the left or right half, without actually trimming any image data (the other half was simply hanging off the left or right side of the visible page).