I have a lot of books full of tables - especially world-building tables. Here are just a few I really enjoyed reading:
The Dungeon Dozen - I keep the print copy of this by my bed so I can flip it open and just read a little before I sleep or just after I wake up. It's good episodic inspiration.
Ready Ref Sheets - an amazing peer into the table-heavy past of gaming. Not that gaming is less table-heavy now, so much as in the past you could sell a book of tables with little or no explanation because we craved anything to help us play. I didn't have this back in the day (I never saw Judges Guild stuff outside of Dragon ads) but it's a fun read now.
The Dungeon Alphabet (review)- this has a great deal to do with me deciding I really wanted to run a dungeon-focused game again. It should get almost as much credit as the DF line and DFA1. I have strong visual connections between this book and a place I was on vacation - I brought it with me on a trip and read it front to back. It really made me want to delve into dungeons again.
Monsters & Treasure Assortment - there is a whole world of inter-language D&D here. It's not quite OD&D, not quite AD&D, not quite anything - it's this weird mix that in retrospect a lot of early D&D books had. They built on knowledge they assumed you had and just seemed odd when you came in later. In any case, this book is just monsters and treasure on different tables. Its a joy to look through even if it oddly lacks details you'd need to use it off the shelf (HD, for example, or THAC0.)
Several versions of DUNGEONMASTERS GUIDE have great tables in them, too, with all sorts of details for the world around you.
But I rarely roll on these tables. I have, on occasion, when I'm really stuck for either meaningless detail I could potentially turn into something meaningful or when I'm just bored. But it is rare for me to do that.
Not only that, but when I do roll if I don't like the result I won't use it. I asked the universe a question, as they say, but disregard the answer. I'm the master of my made-up universe, and the dice are just advice. I need to hear from them to know what I'm actually thinking deep down inside. They get a free hand in combat but not in campaign generation.
I read these books for potential, but I don't roll on them that often. It's just another way to list potential ideas for me.
How about you guys? Do you use tables, just read them, use them occasionally?