Essentials

My names are not colored! / Why won't it display the prefix I configured?

You have to enable "add-prefix-suffix" in Essentials config. Make sure, that "change-displayname" is also enabled.

How do I setup different colored names in chat when using PermissionsBukkit or bPermissions?

Use the group formats in Essentials config like in the example below. Essentials uses the first group in the list of groups as your main group. So if you're configuring groups in PermissionsBukkit or bPermissions, pay attention to the order of the groups of each user or use only one group for each user.

chat:
  group-formats:
    Default: '{DISPLAYNAME}&7:&f {MESSAGE}'
    Moderator: '&2[{GROUP}] {DISPLAYNAME}&7:&c {MESSAGE}'
    Admin: '&c[{GROUP}] {DISPLAYNAME}&7:&c {MESSAGE}'

How do I run Essentials on Mac Leopard / 10.5?

First, make sure you have the latest java updates installed. Open Applications/Utilities/Java Preferences.app and move Java SE 6 to the top of the list. It should look like in this screenshot: