The racial bonuses of Orcs favor two-handed weapons greatly. This means that, if you plan to play a character which utilizes two-handed melee (THF) fighting as its primary activity, you are good to go, but due to the STR-bonuses, a two-weapon fighting (TWF) style is also a good choice.
Naturally, this benefits Fighters and Barbarians, but there are some less obvious class choices which are also viable.
Both Monks and Rogues have access to a quarterstaff fighting tree, which is another good THF choice. The -2 INT doesn't impede a rogue much, as you naturally get a lot of skill points. As TWF builds, monks, rogues and rangers are an OK choice, mainly due to the extra STR.
A melee bard works fine, even as a Half-Orc. With items and tomes, you will still be able to cast the nice spells, such as Haste, Displacement and Rage, but you should not expect to be able to use DC-based spells such as Otto's sphere of dancing. The combination of a powerful melee class with a -2 CHA with the bard class has actually a long tradition in DDO, and has worked quite well (e.g. the so-called axesinger, which is a TWF dwarf bard). If you plan to play a half-orc bard, you can combine it with other classes such as Fighter, Rogue or Barbarian, to get martial weapon proficiency, feats, rage and/or evasion.
Playing divine classes with an emphasis on melee works (you are still expected to provide healing), but the awesome ability Divine Might (based on CHA) will take a slight hit. Along the same lines are THFing paladins: It works, but it's not the best choice.
Wizards and Sorcerers benefit only marginally from the extra STR, but get a hit to their casting attribute. If you want to play your arcane caster as a THF melee, a warforged might be a better choice due access to self-healing.
I can't comment on Druid or Artificer, as I don't have much experience with these.