Had an interesting challenge on Sunday morning - to try and make sense of Psalm 8 as a Messianic Psalm as the first in a mini-series on such texts (the next person has Ps 22). It's funny - I felt distinctly 'off-form' preparing and preaching on it. There's lots there, but I struggled to find the spark I need to preach a sermon that gets near to meeting my internal standards.
I think the central problem was that I wanted to preach on it both as a Psalm in its own right in its original context, and on the extra layers of meaning the New Testament gives it. I ended up preaching on Psalm 8 with a summary of a sermon on Hebrews 2 packed in. It didn't work for me, and I'm not convinced it connected very well, either. Quite enjoyed wrestling with the text, though.