When I attempt to read the 'A Seawitch's Guide' book, it crashes my client.

Mariculture 1.2.2 (occured with 1.2.1E)
Enchiridion (1.1)

Full crashlog: http://pastebin.com/fQdavPrK

I am unable to recreate this crash. I see you have Optifine. Try without Optifine.

I removed OptiFine and it's still occuring.

I can't test it here at work, but tonight I'll see if it occurs in SSP (the crash occurs when playing SMP).

OK I just tested on SMP, and it's working perfectly normal for me.

Some mod you have must be breaking something, you'd have to test to find out which it is, before I'd be able to work anything out. There is no logical reason that you could get a NPE error there, unless something is clearing the data from memory.