I've been hooked on addons since the Runes of Magic community first started making them. I spend countless hours using them to tweak my user interface, on top of having ones that are actually functional. If you didn't know that RoM supports addons or don't know which ones to try, then allow me to breakdown some of the more popular ones for you.
PbInfo started as a handy tooltip feature, but it's grown into a collection of helpful game enhancements that include a threat meter, quest tracker and chat frame changes. You can instantly find out a player's class, level, maximum hit points, mana or even a player's target by hovering the mouse over them. The threat meter tracks aggro for you and party members to help keep mobs targeting who you want them to be targeting, and the quest tracker enhances the games built in system by allowing more control over size, color, and location of the quest window. There's some other nice features that add a timer to the castbar, a time stamp on chats, and a display of exact hit points within a mobs bloodbars. Many of these features can be turned on and off, or tweaked to your preference making pbInfo the most popular addon for RoM.
It improves the search function and provides information to help you get better prices when buying and selling. A lot of what it does is behind the scenes because it's collecting data to get average price ranges for commonly seen items, or remembering bid/buy out price histories. On the surface you can create more specific searches, get color coded per-unit prices to see if someone is overcharging, and get your auction prices auto-filled for you based on past prices you've charged. It's not a perfect machine that guarantees you'll never have to check going rates, but AdvancedAuctionhouse is almost as popular as pbInfo for what it can do.
When you start filling up all the many bank, bag and storage slots you get -- or buy -- with...stuff, it can become a hassle to keep it all in order. Or what if you're at the auction house and can't remember if you already bought an expensive tier 8 mana stone? Inventory Viewer will give you a window that you can check from anywhere that will show every storage slot you have. Your bank, bag, and any storage device in your house -- including mannequins -- are all shown in one window. If you have alts or even multiple game accounts, they can all be categorized into tabs for quick display.
If you want to know how much damage you or other party members are dealing, Scrutinizer will do that and more. Details on heals and everyone's skills can also be seen with the ability to broadcast the information through different chat channels. It can be used as a fun score card for players wanting to compare and see who did better or for groups to improve performance.
StatRating gives an explanation on how runes and other item statistics actually affect your character by placing additional information on item tootips. You can see exactly how many points of health any stamina rune is adding, or if you'd rather have a weapon with a strength bonus than one with an attack bonus. Many stats have different names that appear to offer similar bonuses and StatRating will allow you to stop writing lists or visiting websites every time you need to compare before a purchase.
I'm not quite sure if RoM developers would approve of the name, but it gets the point across. Instead of navigating with the drop-down menus, you can click with the mouse to zoom in and out of zones. The other benefit of WoWMap is being able to click on a dungeon location to switch to an interior map. Some options like turning on and off quest display icons are included, and the original drop-down menus are retained.
The description from the creator mentions qUnitFrames is "...optically inspired by some well known WoW addons." You get streamlined and customizable unit frames for yourself and targets. Easily slide your player, target, and targets-target fames anywhere you want and choose where buff icons appear around them. I love how it simplifies the unit frames while still giving them a nice look. You're not stuck with one design either. There's a nice selection of pre-built styles to choose from to give unit frames a glossy finish or different textures for fitting it in with other elements on your screen.
Honorable Mention: Booty Loot All
This is a personal favorite that hardly does anything, but I couldn't live without it. Booty Loot All adds a 'loot all' button at the bottom of the loot window. Now I could could just turn on auto-loot from RoM's function menu, but then I'd have to take everything all the time. Adding a button to choose per loot window gives more control over what I want -- on the fly. When I'm working my way through kill quests I can easily loot everything the majority of the time, but whenever a useless stone or throwing dagger pops up I just click around it and move on.
Downloading and getting the addons working is painless. You can use the Curse Client to automatically download, unzip, and install them. If you'd prefer manually adding them, you need to create a folder named addons within your RoM directory. Download, unzip, and place the unzipped folder into that RoM addons folder and your up and running.
These are just a few of the hundreds of addons you can get for RoM to change your overall gaming experience. Curse.com is the goto place for them and easily lets you browse by category. If you've been putting it off, maybe now would be a good time to explore them and find ways to make RoM even more fun for yourself. If you do already use some that you think I should have mentioned, leave a comment about what they do and why someone should try them.