With 4E, races are significantly more differentiated from one another than they were in previous editions. To this end, and especially in the case of the PCs (who shouldn't have to be "typical", IMHO), I've given all the races a floating ability score bonus in place of one of their static bonuses, in order to encourage uncommon race/class combinations.
To demonstrate, almost every race in 4E grants a static +2 bonus to two specific ability scores. With my houserule, players choose one of those two static +2 bonuses to keep, and then simply add +2 to any other ability score. (In the case of Humans, players simply get two +2 bonuses to apply to any two ability scores.) For example:
- Normally, Drow PC get a +2 bonus to Dexterity and Charisma. This makes a Drow PC optimal as a Rogue or Sorcerer, for example.
- With my houserule, however, Drow PCs get +2 to either Dexterity or Charisma, and another +2 bonus to any ability score other than the one chosen for their first bonus. This way, a Drow PC can have +2 to Dexterity and Intelligence for a Wizard character, or +2 to Wisdom and Charisma for a Cleric character, and of course, +2 to Dexterity and Charisma is still an option.
The net effect is going to be that Human PCs are very slightly more powerful than usual, but it shouldn't have much of an impact overall (except for making Human characters slightly more common than before).
FWIW, these rules obviously only apply to PCs. My houserule lets Gnolls (for example) be potentially much better Swordmages (for example) than they would normally be, thus encouraging Gnoll players to make a Swordmage. Does this mean that my world is full of Gnoll Swordmage NPCs? Hell no.
Also worth noting is that while this makes every race work with a lot more classes, every race will still have classes that it's not perfect for. For example, Goliath characters will still have a bonus to either Strength or Constitution, neither of which is at all useful to a Wizard character. (However, since a Goliath can now put one of his bonuses into Intelligence, they still have a lot more potential as Wizards than they do under the normal rules.)