Syl at MMO Gypsy has a post on kindness in FFXIV. I'd like to take a look at just what factors inspire people in FFXIV to be kind, using Syl's example of a dead solo player asking for a res.
1. First, the game needs to give players the potential opportunity to be kind. FFXIV's death mechanic could be considered "bad design". In most MMOs, if you die, you resurrect at the nearest spawn point or graveyard. In FFXIV, when you die, your option is to resurrect at your "home point". Your home point might be set to a city on the far side of the continent, because that's usually more convenient, as you get a free teleport to your home point every 10 minutes.
So dying in FFXIV can be more inconvenient than in many other games. That gives other players the opportunity to save the dead player a lot of time.
As well, FFXIV also sends high-level players back to leveling zones, and allows the spell that resurrects people to be taken cross-class. So even if you aren't a healer, you might still have the resurrect spell as one of your cross-class spells.
2. The player receiving the kindness must not be undeserving. If the dead player resurrected at the nearest town, the travel distance for the kind player is the same as the dead player. I bet that in this situation, the dead player would be called out as "lazy" and told to walk back.
In fact, if the norm in FFXIV was to change your home point whenever you switched areas, asking for a res might be considered bad. But the norm in FFXIV is to set your home point to a central convenient city.
3. The game needs to make it easy to be kind. FFXIV has the "<pos>" macro. When you put that in chat, it makes a link with your current co-ordinates. If another player clicks that link, the game puts a small flag on the map at that location. This makes it real easy for a kind player to actually find the dead player. It's relatively minimal effort.
"<pos>" is also useful to call out special targets. Like if you find a Hunt target, people often call it out in chat with the co-ordinates. Very easy to do, and very helpful.
The more effort being kind takes, the less likely people are to be kind. This also applies to costs. The higher the cost of being kind, either in actual cost or lost opportunity, the less likely people are to be kind. This is often the problem with dungeon groups.
4. Kindness works best if only a few people need to be kind. Of all the people seeing the "Needs Res" message, only one or two people need to respond. If the majority of people don't respond, the dead player still perceives the community as kind, so long as at least one person does respond.
Again, this is another problem in formal group play. In groups, usually everyone needs to be kind. Here, one unkind person can hurt the experience, and cause the person to perceive the entire community as being unkind.
Kindness is actually fairly hard to cultivate. There are several factors that need to work to get it right. I think FFXIV does a good job, but I am not sure how much is actual design, and how much is just serendipity. For example, I was just in a rather acrimonious Crystal Tower run that was pretty much as bad as anything you see in WoW (mostly because we wiped on Bone Dragon once because everyone ignored the skeleton mechanic).