My 3 picks would be (in order): Conan OGL, Grim Tales, Iron Heroes. I believe Conan is available in PDF. As stated earlier, a 2nd edition is due out (August?) but hints thus far are that it's consolidation, tweaks, and cleanup rather than a massive re-write. The current version is fully functional, however.
I've adopted Conan OGL as my baseline rules set since swords-n-sorcery is my preferred style of play and the Conan OGL is the most comprehensive D20 take on swords-n-sorcery I've found.
Character classes include Soldier (tweaked Fighter), Barbarian ('nuf said), Borderer (finally, a non-magical outdoor-oriented warrior), Nomad, Pirate, Thief (no sissy rogue), Noble, and Scholar (includes sorcerors). A Temptress class (workable PC class to boot) was added in the Hyboria's Fallen supplement and is rumored to be included as a core class in the 2nd edition. A bandit class was introduced in Mongoose's Signs & Portents magazine and was recently reprinted in the Conan Compendium. It's a blend of borderer and pirate in some ways so it appears it will remain an optional class.
Combat was tweaked significantly to make it grittier. Armor acts as DR (as it should), weapon damage is higher, Massive Damage is grittier, and Hit Die caps out at 10th or 11th level.
The game is also very true to the source material. The authors of the game and supplements go to great lengths to identify non-Howard sources so that Conan purists can ignore them if desired.
Grim Tales tweaks standard d20 (D20 Modern actually) to create a grittier game. It's a terrific toolkit. I use it when I want to build something from the ground-up that isn't covered by Conan. Also if you want a middle-ground between D&D's high-fantasy spellcasting and Conan's corrupting sorcery, GT has a good spellcasting system that allows you to preserve the D&D spells while maintaining a swords-n-sorcery feel. (Thieves' World Players' Manual also does this.)
Iron Heroes has several books out, including a new Companion book. Some of the books will have to be purchased as PDF, however, as the printed copies have either sold out or go for top $. Iron Heroes can do S&S very well, as it removes D&D magic items, replaces core classes with various warrior-variant classes, and modifies spellcasting to fit the genre better. Of the three that I've listed, however, Iron Heroes is the most cinematic. It was designed to maintain the D&D power curve, just without relying on magic to do so. Conan and Grim Tales are grittier.
Azgulor