Here are some of the transitional fossils I have blogged on in the past year:
The Missing Link to Archaeopteryx
Transitional Bat Fossil
Indohyus: Early Whale?
Crocodile 'Missing Link'
These only add to massive amount of transitional fossils we already have. (Click here to see some pretty pictures of them).
I was doing a search on National Geographic, and I felt I ought to mention this fossil as well, which shows the transition from Homo Erectus to Homo Sapiens. I may do a post like this on the observed cases of evolution I have blogged on in the past year. Their are certainly some interesting ones.