The Organize Series WordPress Plugin helps with the organization and presentation of articles/posts you write as part of a series. It helps make it easier for readers of your blog to discover all the series you’ve written and also to easily find post that are part of the same series.
Organize Series actually adds a new taxonomy to the WordPress taxonomy structure so your blog would have “categories”, “tags”, and “series” as the taxonomy types.
Make sure you check out the features section in the “other notes” tab for all the neat stuff you can do!
As of version 2.4.6, Organize Series requires WordPress 3.7+ to work. While Organize Series may work on PHP5.2 it is recommended (and supported) for PHP5.3+.
NOTE: Organize Series has not been designed to be multisite compatible at this time. Some users are finding it works great for their needs but your mileage may vary. Feel free to try on multi-site but at your own risk.