Vivian Grey, volume 1 has one of the best dedications I've read. You "will accept and appreciate the compliment," even those of whom the compliment is not directed at.
The Complete Confectioner has the longest title I've come across: The Complete Confectioner; or, Housekeeper's Guide: to a simple and speedy method of understanding the whole art of confectionary; the various ways of preserving and candying, dry and liquid, all kinds of fruit, nuts, flowers, herbs, &c. and the method of keeping them fresh and fine all year around; the different ways of clarifying sugar; with directions for making fruit pastes, bomboons, pastils, compotes, fruit ices; cream ices, marmalades, jellies, jams, cakes, puffs, biscuits, tarts, custards, ckeesecakes, sweetmeats, fritters, creams, syllabubs, blanc-mange, flummeries, ornaments for grand entertainments, dragees, syrups of all kinds, nicknacks and trifles for deserts, strong cordials, oils, simple waters, milk punch that will keep 20 years, and all sorts of English wines; also, the art of making artificial fruit, with the stalks in it, so as to resemble the natural fruit; to which are added, some bills of fare for deserts for private families.
When You Write a Letter, another amusing dedication. "To my former students and all others who have not answered my letters".
↑From index creation to validation of all page took 17 minutes, though two hours and one minute to mark the index as done (all validated). The quickest for a text that I have added.