Notepad++. text editing
Calibre. conversion to and from various eBook formats
IrfanView & MS Paint. image manipulation and conversion
Mozilla Firefox. preview and testing of source HTML
XAMPP for Windows. execution of custom PHP scripts for retrieval of web content and process automation
rsync. synchronization, backups, etc
Stanza for iPhone. for actual reading of generated eBooks, still undecided on what eBook reader to buy