Choose one piece of proprietary software that you use regularly and find its FOSS equivalent if it has one. (If not, pick another program.) Write a blog post comparing the two. Don't just look at the code; look at the entire experience. How are the user interfaces different or similar? What about the user's experience overall? Is the quality of the documentation comparable? Is one buggier than the other? (This may take some spelunking in forums, looking for bug reports, etc?)

What, in your estimation, would it take for a new user to switch from the proprietary, closed-source software to the FOSS equivalent?