On RPGNow's top 100, Perils of the Sunken City is #16, the core DCC rulebook is #17, Sailors on the Starless Sea is #20, Sepulchre of the Mountain God is #23, The 13th Skull is #33, People of the Pit is #34, Bone Hoard of the Dancing Horror is #35, The Emerald Enchanter is #42, Jewels of the Carnifex is #43, Alternate Occupations is #48, Attack of the Frawgs is #49, The Ooze Pits of Jonas Gralk is #53, and DCC RPG Free RPG Day 2012 is #77. Since I started paying attention, every new DCC product has occupied a spot in the Top 10, often for an extended period.
In other words, if it is DCC, and it is available on RPGNow, it is in the top 100. AFAICT, only one Pathfinder product appears in the Top 10 (or before Perils of the Sunken City) and at a quick glance, I don't see 4e represented at all. I would guess that this is an indicator that Dungeon Crawl Classics is doing very well. In fact, it seems that a plethora of games are doing well. The 800 lb. gorilla seems to be on a diet right now, leaving plenty of resources for other flora and fauna.
Cathbad the Meek (herbalist Wizard 1): AC 9; 4 hp; S 7, A 7, St 10, P 17, I 13, L 8; Neutral; Club, herbs, 50' rope, 50 cp; -1 to melee attack rolls. Hideous scar.