Daily rewards now became Daily Bonus since 3.0 Patch. You receive increasing gold amount by playing the game [internet required] on consecutive days.
As of patch 1.6 patch Daily Rewards have been removed.
Daily Rewards were introduced with the Heroes vs. Monsters 1.2 patch, on November 27th, 2011, and changed with the Heroes vs Monsters 1.5 patch, on December 23rd, 2011. When the player first logs back into the game, a new chest icon will appear on the map. Once the player moves their Heroes on the chest, they will be rewarded with random loot.
The 1.5 patch introduced scaling item quality the more consecutive days played.