Just like youtube, slideshare is a free service. However for larger presentations (with Hi-Def Photos) or even videos, you may need to buy the Pro Version which enables up to 100MB uploads per presentation.
By the way, I absolutely loved Powerpoint 2013, I thought it was just an amazing tool. My two favorite features were the auto-align and spacing which make it easier to draw block diagrams like the ones in my presentation that are equally spaced and aligned, trust me, that makes the presentation look far more ‘professional’.
The second feature was the File button, no longer drops down a menu, but takes you to a whole new screen, that enables you to save the presentation to your ShareDrive. Even the Beta version of Powerpoint feels far more cleaner and intuitive than my current version of Office 2007. I guess Microsoft has come a LOOOONG WAY in 6 years, good one on you Microsoft.