Ed Bourelle, creator of e-Adventure Tiles, gives away more quality content for free than some publishers produce in an entire year. This collection is no exception. In addition to a full arena set (a staple of any major Underdark culture), this annual contains tiles from a wide variety of other sets. There's a passageway with a ten-foot wide spider web, an entrance with two coffins overlooking blood-colored pools, a fancy bedchamber, a set of deciduous wilderness tiles, the entrance to desert ruins, a graveyard, mine carts, a "sacred altar" with blood on it, sewer grates, boats, and something called a mechanical monolith.
I was able to create an entire map using this set alone for a showdown with Eihort in my Call of Cthulhu campaign (specifically, Cross My Heart and Hope to Die from Goatswood and Less Pleasant Places) by printing out the deciduous forest tiles, the sacred altar, and the wide cave connection. And it didn't cost me a dime. Thanks Ed!