In Djinn Rummy, British comic fantasy writer Tom Holt takes the old "Genie in the Lamp" premise (or in this case it's an aspirin bottle), recasts it in the present day and has a lot of fun turning it to his own far fetched ends.
Their are some fairly remarkable plot twists involving druids, giant carnivorous plants, plagues, Iraqi fishermen, electronically controlled magic carpets, wimpy shop assistants and Cupid that keep the plot moving along at a breakneck pace.
There isn't a whole lot of logic to the plot mind, in fact it's debatable if it's even that important. The book depends on Holt's ability to create interesting characters and his witty descriptions of the predicaments that they find themselves in.
There is the likable anti-hero Kiss, the love-struck genie with the acid tongue who finds himself in the inconvenient position of having the fate of mankind resting on his shoulders. Then there is the psychotically evil Philly Nine, who loves nothing better than to wipe out all humankind when he's not pursuing the favourite genie pastime of acquiring wealth beyond the dreams of avarice. The human characters are less interesting; this book is all about the genies.
If you like Terry Pratchett or Robert Rankin, you'll probably be fairly well disposed towards this book. It does not operate in a purely fantasy environment like Pratchett's Discworld, and it is not nearly as anarchic or off the wall as Rankin's work but it has its moments of inspired lunacy. While it isn't necessarily laugh-out-loud hilarious all the time, it is quite clever, never boring and an enjoyable read throughout.