The big problem with Olympus is that the full reference manual only appears on the CD with the camera, you have to pay extra to get a printed manual. Poor behaviour as the full reference manual is essential to everyday operation. The multi language starter manual is very basic and doesn't mention many essential features. 
 

Finding Digital Camera Manuals: To make this page easier to maintain as new models arrive, I've found the two best links for finding literature. One is for USA and one is for Asia/Oceania but you will find the manuals are the same. 

Try        www.olympusamerica.com/cpg_section/cpg_download_manuals.asp  

or          www.olympus.co.jp/en/support/imsg/digicamera/download/manual/      to search for manuals and other brochures.

For E-1 Literature as an example.... Open www.olympus.com then choose USA region, then select Digital Cameras in the Consumer Products, then select E-1 System. In the E-1 window select Q&A Support-Literature and you will get to the page of PDFs for all E-1 System components.

Olympus Software Upgrades....  As they become available (and that now includes camera firmware) they all appear here. USA readers may like to look here for the same sort of information. The Camedia software (March 04) updated from V4.1 to 4.2 and I only knew it because I happened to be checking the update page  looking for something else. There's also V4.3 at the USA site but evidently there's not much need to change from 4.2 to 4.3 but I did anyway with no ill effects.

Olympus Camera/Lens/Flash updates.... There is a general program (Windows and Mac versions available) for updating Olympus cameras and lenses and flashes for cameras made after 2004 and also for adding a new language to the camera. 

Find it at http://www.olympus.co.jp/en/support/imsg/digicamera/download/software/camera/cameraupdate.cfm

It recognises my E-300 which was announced September '04, but untested by me is E-1 which was announced June '03.