Data Cleaning & Transformation
Powerful tool for working with messy data, cleaning it, transforming from one format to another, and extending it with web services or external data. Although not a Python library, it's valuable for advanced data wrangling alongside Python tools.
Web Scraping & HTML Parsing
Library for web scraping and parsing HTML/XML documents. Extensively used in data wrangling to clean, parse, and extract data from web sources.