I'm a big widget user (have 20+). I won't list them all, but here are some of my favorites:
News - Apple Widget
BeWeather - best weather widget in my opinion
ESPN - sports scores for your favorite teams
Fantastical - best calendar widget in my opinion
Widgetter - social media updates (twitter, etc.) and it's free
Google Maps - local transit
Slingplayer - if you have SlingTV, it lists now playing shows for your favorite channels
TVGuide - Trending Tonight
TeeVee - Tracks when your favorite TV shows will play
Amazon - Search, track shipments, etc.
Musixmatch - Music Lyrics as you listen
Seatgeek - Upcoming shows in your area
Itranslate - translate copy/pasted text
LoseIt! - Track calories
Stepz - Shows Steps/miles walked
Find Friends - Apple Widget
Top Chart - Free widget that lists top apps/music/movies, etc.
Hope this helps.