MobiPocket Reader

Before anyone says anything, I know that it is not opensource and that the source code is not available. I think it would be nice to have a portable version on my thumbdrive. I'm no good at programming, so I can't do it myself, but surely there has to be some way of making it portable. M$$ Reader would be a good one to have as well. I have ebooks for both platforms, but no way to read them. Now if what I'm asking is impossible, let me know and I'll live with the world I'm given. If there is some other reader out there that is opensource that can read these formats, than that will serve my needs as well. Thanks for your help and consideration.