The free OpenOffice.org has a very handy export to PDF function. However, as with other PDF creation tools, unless you are careful the files created can be very large. One way to make smaller files is to use the fourteen typefaces built into PDF. These are the so called "Base 14 fonts": Times/Times Roman, Courier, Helvetica/Arial, Symbol and Zapf Dingbats (in regular, bold, italic and combinations thereof). If you use these fonts carefully, the PDF file need not contain a copy of the font, and the resulting file is much smaller. The catch with this is that the font used for display may not be precisely the same as on your system, but for most documents this does not matter.
As an example, the draft of my Senate Submission on the Carbon Pollution Reduction Scheme is an 18 kbyte word processing document. The senate publishes submissions in PDF, so I thought it best to give it to them in that format and avoid conversion. When I exported the PDF from OO it was 97 kbytes. This is not a particularly large file, but not as small as it could be.
My document was in Times, but apparently not the standard PDF times, so a subset of the times font was included in the PDF file making it bigger. Changing the document to Ariel did not make the file any smaller. When I tried Helvetica, I discovered I didn't have it installed on my PC, but could still type it into OOO as the requested font. When I saved this version it was only 23 kbytes and so not much larger than the OOO original. On my computer the Helvetica is converted to Ariel, as that is closest.