I use MobiPocket every day to read books but I am always open to alternatives. Chonka let me know that eReader has released a BlackBerry client for their eBook store. I remember eReader back from my Windows Mobile and Palm OS days so it is a bit of a flash from the past. Their website is in desperate need of a redesign but the application seems to be working quite well. I would offer screenshots but every time I try to take them it crashes my Mac (VMware Fusion/XP). Hopefully somebody can send some in!
The cool part about this eReader beta is that is has controls specifically for the Storm. The eReader eBook reader is free but the application to create the eBooks yourself is not. On the other hand they use a eReader .PDB (Palm) file if I remember correctly that I think a few free eBook makers can create… Not positive though.