We have essentially three major ways to see which of our friends are online:
1) "Friends" toolbar button
2) Calling Card category in inventory
3) "Friends" drop-down in Map.
Perhaps there are others that I am forgetting, but hopefully I've covered them all.
Now of these methods, there are a few items of note that are inconsistent or need to be improved upon:
1) Filtering. Currently, there's no easy way to get a list of JUST those friends that are online (other than, ironically, the SL website). SL really needs something equivalent to the "Hide Offline Buddies" option found in many IM clients. Additionally, categorization of Friends *outside* the Calling Card portion of inventory is next-to-worthless.
2) Recent changes to the way calling cards are treated (i.e. showing their permissions in the inventory list) make them hard to use for online status. This is because many (or perhaps most) users keep the inventory list somewhat narrow, which cuts off the "

3) Map. The ability to see *where* a Friend is located is very useful, but unfortunately there's no easy or intuitive way to get there. I myself use two methods - one is pulling up the map and selecting their name from the drop-down, and the other is Calling Card -> Properties -> Profile -> Map (or with the introduction of 1.6, Friends -> Profile -> Map). The first method isn't intuitive for new users (they would really expect to see this as an option in the Friends list on the toolbar) and the second is too tedious. This should be a top-level option along with other actions such as IM, Pay, etc.
4) Presence. Right now, it's not at all obvious how to go into busy mode, and this is actually seperate from the rest of the Friends list. This ought to be part of the Friends UI, and it would be nice to see this expanded upon to include more presence options.
Overall, I'd like to see a good overhaul of how the UI treats Friends. If I were LL, I would look to one of the better conventional IM clients (Trillian, perhaps?) for ways to handle list management, presence, notification, and actions. Why re-invent this part of the wheel when a proven model already exists that users are familiar with??? Because *socializing is such a huge part of SL and a selling point for LL*, I believe that features enabling you to keep in touch with friends, business associates, etc. should be #1 on the priority list.
-N