Bernard Cornwell cites:

Wellington at Waterloo (Jac Weller) Wellington, the Years of the Sword (Elizabeth Longford)

I know this may not be too helpful unless you're going there, but the video they show at the Waterloo visitors center is very helpful in visualizing the battle. It uses a lot of footage from Sergei Bondarchuk's 1970 film "Waterloo" (which, in itself, is well worth watching, but the maps and blue-red arrows make climbing Lion's Mound and looking out over the battlefield much easier). The film was a joint Soviet-British production in 1970, and Rod Steiger and Christopher Plummer are both excellent in it. My biggest question/critique is around Steiger's portrayal of the level of doubt Napoleon had; I simply don't know if this reflects the best understanding of history.

Also recommended for entertainment (though others can comment on the historical veracity) are both the book and movie of Bernard Cornwell's "Sharpe's Waterloo." The appendix covers some of the controversies.

Cornwell also has a new book out on Waterloo which I have not yet read..

Funnily enough this pic http://i.imgur.com/vAygOQZ.jpg just got posted on /r/Ireland by /u/Tybalt42

It's a 15000 piece toy solider recreation of the battle set up at a toy solider factory in Kilnmartyra Co Cork.

Captain William Sibourne made a scale model of the battlefield in the 1830s, I believe it is still viewable at the National Army Museum in London.

It probably the most accurate portrayal of Waterloo as he toured the battlefield and painstakingly mapped the topography. The fields, trees, hills, ect. are all the correct color and correct location/elevation. He also held dozens of correspondences with the British and Prussian officers that were present during the battle(French officers he contacted were not eager to relive a defeat). He was also granted access to extremely accurate records and dispatches from the Prussian army archives. With all this information he placed at the regiments, with their correct colors, at their correct location during the "climax" of the battle. He also wrote a rather thick history of the Waterloo Campaign.

There was a lot of controversy surrounding the model and the model maker in the 1830/40s. Peter Hofschroer's Wellington's Smallest Victory is a somewhat interesting read recounting Sibourne and the model.

The National Army Museum's page for the model here with some decent pictures, but they really don't do justice to the model's size.

John Keegan's The Face of Battle gives an enlightening view of what the Battle of Waterloo would have looked like, though the primary focus of his work is the practical mechanics of battles throughout history, the historiography of the 'battle piece', and popular myths about battle.