You know how enjoyable it can be to read (and re-read!) a popular fiction series? Each time you finish a title, you look forward to the characters, and perhaps even the story, continuing in further volumes. There's a mix of suspense and comfort in plowing through an entire series such as Harry Potter, the Lord of the Rings, Discworld, or the Aubrey–Maturin books that I'm currently reading.
Nonfiction series may not offer much in the way of suspense between volumes, but finding a good academic series that touches on your specific research area can certainly be rewarding. Each new title is both familiar and new, with different aspects and perspectives of the topic explored in every volume.
I thought I'd highlight just a few of the academic book series I've been keeping an eye on lately...