I don't have photos or screencaps on these, unfortunately, but I wanted to address them. Ong Bak is the most marginal audiovisual upgrade, but it looks a hell of a lot better than the extremely lackluster DVD transfer. That's not really saying too much, however. I'd wager that the same HD master that was used on the DVD got re-used for Blu-ray. Even though it's higher resolution, this looks like a master intended for the much lower-rez DVD world.
Walk the Line and The Last King of Scotland are solid blugrades, but one should be aware that Line does not include the Extended Cut via seamless branching. All the same DVD SE extras remain on all three, albeit in SD.
Now & Then is a sub-feature of the HD Guide that gives a look at what's gained and lost as various titles make the leap to Blu-ray from DVD.