I put together a file list for my friend and decided this might be of use to others too.
This is what I've got in way of add-ons.
I mostly get them at:
http://www.wowace.com/files/ (Sort on timestamp to get newest on top)
http://www.wowinterface.com/index.php? (New and updated add-ons on the right side)
http://wow.curse-gaming.com/en/files/addons/ (This used to be my favorite, now WoW Interface is, but they still get stuff.)
(Some of these add-ons come with multiple parts in their own directories. (I.e. dependencies.) I'm not showing those. I'll just show the main directories. If you get all these you'll have more files in the add-on directory.)
Backbone of the Ace add-on system. This is a support library that other "Ace based" add-ons use. Memory efficient. Get it because a great many of the below are based on Ace2.
Tells me how long I've been playing. "How can you kill that which has no life?"
The loot to be found. Handy when you're asking yourself "Do I want to go raid Hello Kitty Fantasy Island? What's in it for me?"
Are you sure you got every quest there?
This is working. Get it at http://auctioneeraddon.com/dl/AuctioneerComplete/
This provides a quick bar for drink, food, mounts, etc. That way I can keep my action bars free for spells.
I primarily used this for auto-joining BG's. It'll also auto-repair your stuff when you visit a vendor that can do repairs. It'll auto-decline duel requests. It'll auto-accept raid and party invites and warlock summons. Etc. You can have it do what you want.
This will automatically sell off your gray items (i.e. vendor trash) in your bag. (You can set stuff in a "save" list so it won't be sold.)
This is my action bar add-on. So I can have my bars where I want them.
Shammy totem bars. This doesn't work as as the previous version yet. But it works.
I absolutely love the info you get in AB and AV with this.
This is like super-Gatherer+. (Get all the Cartographer add-ons as well. Mining, Herbalism, etc.) Very handy world map tool. And in AV you can see all your raid in little circles numbered by group. The class of the player is shown by color of the circle. And if the circle is flashing red you can see that they're in combat. Imagine knowing exactly where every fight is in AV. (Or AB.)
I keep this and Healbot so I can do more. (This is good for when you use Grid (below) and where the raid would otherwise overwhelm Healbot.)
"Skins" the Bartender bars and more.
How much DPS am I doing? How much healing am I doing?
This makes buying warlock pet spells easier.
This provides the setup options for other Ace add-ons in one place.
This will allow unit frames to show the Druids mana when he's in other shapes. (You'll recover mana after shifting to cat or bear form. Handy to know when you're full again.) Has it's own bar, or it'll provide the info for other unit frames (like X-Perl below.)
I like the info on buffs and debuffs.
Is that robe really better?
Provides some idea what you're after in the battlegrounds. Relevant mostly for 60's with lots of time on their hands.
I like info. I used Titan Bar until I found that the Ace/Fubar collection was much better memory wise. And FuBar tends not to be. (Army acronym.)
Should tell you if that recipe/pattern/schematic you see for sale in the auction house is sold by a vendor somewhere. Should.
If you're a hunter you can use these. If not, ignore.
I like this for raids. It'll do a compact 8x5 grid of everyone in AV. Then you can see their class, health, etc. This is where Clique comes in. I can shift-click on a person's box to heal them, for example.
CastParty/ClickHeal add-on. This and Clique about covers it.
This is AV magic for hunters. Target the enemy off your radar like you're some spy hunter.
Got time for that bio?
How good is that item? No, really. "Level you can use at" is not equal to "level of how good it really is."
This is your weapon/outfit swapping add-on.
It loads with a heart beat. I think it works.
A very configurable Hud.
This is a Scrolling Combat Text competitor.
This will tell you how much health that mob really has.
This arranges your bags. Handy.
This is a nice set of inventory add-ons.
I don't raid much, but when I did raid this fired up the Main Tank's targets. It's supposed to work with CT_Raid.
My chat channel has never been more organized.
Hmm. This does something.
This comes in handy for leatherworking, engineering, etc. Where one item is made of other items that are made of yet other items. Try it.
This really works. I love the info I get. I hate it when I'm crit for *1337* by a rogue. Punk.
This is a crafting queue.
For those that need to compare themselves with others, and compare those others with yet others. I got it a while back because it's how I tracked my own +Healing and +Resist info.
ItemRack will handle trinkets. This is better.
This is similar to ItemLevel. However where ItemLevel looks at stats, this goes a step farther. This appears to be a realistic item level.
I used to use Classic Perl Bars. Now I use XPerl because I like the configuration possibilities better. And there's arcane bars for most units. And it looks good. I like it a lot.
This is a collection of hunter add-ons providing pet, aspect, tracking, trap pull-down action bars. Handy to free up your own action bars for /emotes. I keep the pet, aspect, and trap menus enabled. I use the GFW tracker add-on.
Anyway, that's what I play with.