And here's the screenie :)
Honestly, tons of unorthodox builds are viable at lower ELOs, and even mid ELO. People probably sneer at me when I run Cho'Gath with Clarity+Ignite. This sneer disappears once they realize that they make about 80 gold a minute because they have to hide -way- back to avoid constant Rupture harass fueled by Clarity and Cho's passive. Combine this with early game Regrowth Pendant and you have Cho'Gath - The Jerkass of the Void, using his amazing staying power to deprive the enemy champs of gold, XP, and liberty. If they question Cho's early game domination and make themselves out to be daredevils, Ignite is a good way of teaching them their place.
And then I eat them, of course.
Mid game, I go home and put on some boots, Warmogs, and work towards Atma's Impaler. Note that this is due to generally ****ty team composition in solo queues, so there's either a second tank on my team, or the enemy team lacks the damage output to warrant further beefing up of my Cho build. This naturally progresses to 300 damage crits and the enemy team's starved champs running in fear at Cho'Gath's ability to do about 2000 damage and then set you on fire within a few seconds. Against competent/premade teams, you need Guardian's Angel, Banshee's Veil, etc. so you can't afford to waste cash on an Infinity Edge. However, if you did a good job at harassing the **** out of the enemy team early game, you can probably indulge in more AD items and solo devour squishies/carries in the jungle during midgame.
Late game, Cho'Gath is still a 4000~5000 HP monster despite also forking out 300+ damage crits to the enemy champs. While this does mean you have **** for armor/magic resist, people generally see all of the black lines on your health bar and **** themselves in terror regardless. In team fights, your HP and the fact that you're Cho is often enough to deter the enemy team from dealing with you. This is a critical error, because you're built to crunchify anything that isn't a tank. They will soon discover this.
My Cho build isn't high ELO by any means, but often, the conventional Cho build actually fails a fair bit in lower-mid ELOs, where stacking armor/magic resist is excessive against rather incompetent opponents, and your teammates aren't always smart enough to take advantage of the sheer resilience and AoE debuffs you're spitting out. From my experience, more firepower would make it so you don't have to rely entirely on sometimes unreliable teammates to gobble mother****ers up.
Also, it's always fun out DPSing the enemy carry.
p.s. @ Clinz, having 2000 HP 23 minutes into the game makes you anything but a tank. You're basically assuming that your opponents are all trash and don't know how to nuke you or use CC, but since that seems to be working out for you in your screenshot, rock on, buddy.