Science 
I ordered Jerusalem through the library, I was eighth on the list, it looked like I would never get it :(
So I bought it on the Kindle, flicked through and decided to keep it 
(by the way, made the conchiglie with yoghurt, peas and chilli, on the recommendation of Orangette, and it was amazing. Far better than it sounds from the list of ingredients)
Got the Madhur Jaffrey book from the library, didn't fancy it, sent it back.
Got HFW Veg ages ago from the library, again nothing grabbed me (veggie since I was 15, nothing new in the book it seemed), sent it back
Got the other Fuchsia Dunlop book out ages ago, very meat-based, so sent it back
The ones I bought, I read rave reviews on Amazon, also looked at the index on Amazon. Of course, I got the ideas from you lovely ladies.
And they have filled 'gaps' in my bookshelves. Except I have run out of space, but you know what I mean. I needed a good curry book, a good chinese book, I had no Mexican at all.....and I have been thinking of getting Jerusalem for ages, but thought I didn't need it. Probably didn't really, as it is quite meaty, but I do love Yotam :)
I am on the waiting list for Prashad from the library!
(just read this back and sound like I'm defending my spending habits! Sorry, obviously have some guilt there!)