Many portmanteau words have come into use since 1993, when Portmanteau Dictionary: Blend Words in the English Language, Including Trademarks and Brand Names was published, but it's a huge collection and you can pick it up used if you don't want to pay the steep price of a new copy.
Some other books of interest to word junkies...
You can also see portmanteau and other delightful word play in action in Lewis Carroll's writing. Check out Alice's Adventures in Wonderland and Through the Looking-Glass or Lewis Carroll: The Complete Illustrated Works: Alice's Adventures in Wonderland, Through the Looking-Glass and What Alice Found There, the Hunting of the Snark (Literary Classics)
If you love words, you'll love A Word A Day, a short but sweet word celebration.
And, even after all these years, The Joy of Lex is still one of the most entertaining books around.
You might also want to check out our Random Adjective-Noun, and Random Verb-Adverb pages, as well as the main Creative Concepts Consulting homepage