Aldiko is a great Android App to read your ebooks right on your mobile phone.
You can import the epub ebooks you already own from the sdcard. Non epub format DRM-free ebooks can be converted to epub format using Calibre software.
As editors like O'Reilly, Manning, Mark Murphy's CommonsWare have started to release their books in DRM-free ebook format, the mobile as an ebook reader is becoming more and more a reality.
The QR-code to access the Aldiko app on the Android Market is here.
SlideMe app market on the Aldiko blog post but I can't find it.