Foxit PDF Editor
This handy little program lets you edit PDF files, adding and removing pages and elements, and tweaking text. It also does a decent job at creating and editing graphics. The free demo version adds a watermark to your saved files and displays nag screens; registering the program for $99 removes these inconveniences.
One caveat: Foxit PDF Editor is not a full-fledged layout program. For example, it treats all elements as graphics--so if you try to resize a text box, you'll get distorted type. It's a good idea to download and read the free manual before you get started.
Foxit PDF Editor is a good choice for anyone who needs to edit text and graphics PDF documents. If you just need to annotate PDFs, give Foxit's free PDF Reader a try.