Oliver, I know a little about computers and software, but not too much. It would probably help if you tell us what kind of computer you have. Do you use Microsoft Windows Xp? Vista? Mac?
If you use XP (and maybe Vista) you can try this... Open Windows Explorer and locate your PDF file. Right-click on the file and select Send To -> Compressed (zipped) Folder. I tried this on an 11MB PDF file, and it turned it into a little under 3MB. That's probably still too big to post here, but you should be able to email this file to a few people if you (and they) have a high-speed Internet connection.
If you only have a few pages in the PDF file, another way using Windows is to make a JPEG of each page using the Paint software tool.
Open the PDF so you can see the page.
Then simultaneously press the Alt and Print Screen keyboard buttons.
Then open the Paint software tool (Start -> All Programs -> Accessories -> Paint).
Then simultaneously press Ctrl and V. This will put a copy of the page in Paint.
Then save it as a JPEG (File -> Save As and select JPEG under Save as type)
I hope that helps.
Mike
