I'm a big fan on solo top, and Hecarim fits this role perfectly. He has good AOE and can cause mayhem if built right. Devastating Charge and Onslaught of Shadows gives him just enough CC to be a pain as well.
Building him dps/tank is the most reliable build, you do not have to rely on Champion kills for gold, and being a close range fighter you can innitiate without being taken out of the fight.
Pros / Cons
[*] Tanky (if built by this guid)
[*] Good Aoe
[*] Decent CC
[*] Great initiater
[*] Have to be in close range
[*] ...there has to be something else...
Teleport and Ghost. Period. Teleport to get back to your top lane quickly, also to get to the other lanes when they need help. Ghost to keep up with champions, or escape, and it helps with Devastating Charge damage.
Using a mix of offense and defense makes it so Hecarim can farm while staying in lane for long periods. I have not played around with masteries a lot with Hecrim yet, but these are my default tanky/dps masteries and runes. I use gold per level quints in all my rune pages. They are just awesome.
Start off with a pendant and 2 health pots. When you get somewhere around 1000 gold, head back to base, buy tier 1 boots and a Tear of the Goddess. Hecarim's Rampage makes hiom a prime cadidate for Manamune. Depending on what the other team has, more AD or more AP, build either a banshee's veil or frozen heart. Both items have lots of mana, and will help out your manamune later. Once that item is done, buld merc treads and finish off your manamune. Normally from here, I just keep on building tanky with a guardian angel, and either frozen heart or banshee's veil. (whichever I didn't build earlier) But, if you like to damage, then build a phantom dancer and/or trinity force. Usually games don't go on for this long.