Lately my manager here at The Center for Learning Innovation shared some eBook links and i have already finished reading some of them. Most of them regarding best software development practices and application performance. I found them very useful and thought you would also like them. I would highly recommend this books for developers who has just started object oriented design and want to adopt best practices in this field. No matter in which platform you work, it will definitely enrich your arsenal to fight against different development challenges. 

• Foundation of Programming - http://codebetter.com/media/p/179694.aspx
• Applying Design Patterns - http://amazedsaint.blogspot.com/2009/06/software-design-patterns-for-everyone.html
• SOLID Development Principles - http://www.lostechies.com/content/pablo_ebook.aspx
• 31 days of Refactoring - http://www.lostechies.com/media/p/27197/download.aspx

You are probably aware of the following eBooks from Microsoft, they are pretty big (to be honest, i have read only some chapters) but worth reading if you are working in .NET 

• Improving .NET Application Performance and Scalability - http://www.microsoft.com/downloads/en/details.aspx?FamilyID=ce40e4e1-9838-4c89-a197-a373b2a60df2&displaylang=en
• Microsoft Application Architecture Guide - http://www.microsoft.com/downloads/en/details.aspx?FamilyID=8A2E454D-F30E-4E72-B531-75384A0F1C47

Thanks to Refky, for sharing those with me and I hope you will like them.