Third Party Programs
***Note - Because of the changes the expansion made to the core client, Decal had to be radically rewritten! Many old plugins don't work and will never work again.***
AC's user interface isn't exactly the best in the world. More recent game releases have improved on the UI, but AC can still compete! Why? AC has a slew of gamer/programmers who spend their time writing plugins for AC. There are a wide variety of plugins you can download and use, ranging from plugins to help you communicate to macros that play the game for you. Of course, whether or not you use plugins or not and which you use is completely up to you. If you do decide to use plugins, I have my own suggestions on which are most useful.
First of all, practically every third party program is written for another program called Decal. Decal is basically a secondary UI that pastes itself into the AC client. Each plugin you use adds itself to Decal. Each time the game is patched, Decal will be unusable for a few hours to a couple days, until the players who built Decal go over the updated client and find certain memory locations. You can find Decal HERE. Make sure your system meets the requirements and that you download the extra files necessary to install and run Decal. Once you have Decal up and running, be sure to click the update button to get the most recent memlocs. Be aware that anytime the AC client is altered by a monthly patch or hotfix, Decal will break. Decal's Developers are quick to fix it, but the new memlocs are usually not available for a day or two after each patch.
Aside from Decal plugins, there are a good deal of other 3rd Party programs available, some of which integrate into the AC client and some that do not. If you need to find a route, try Dereth Explorer. You can also browse dungeons if you want to find a nice place to explore or level. If you have two accounts and want to play on the same computer, you will need a dual-logging client. My favorite is Drakier's client. Make sure you follow the instructions to the letter, as there are several changes you need to make to be able to dual-log. Of course, you can't log in two characters from the same account no matter what you do.
There are a slew of other plugins available... if you're looking for a particular program, check out Dereth.info This site has pretty much every 3rd party program for Decal, as well as a couple other utilities. In case you're curious, I use three plugins - Alinco, Quest Timer, and DCS (Dereth Color System). Alinco is a multi-purpose plugin that allows you to scan the environment for specific monsters, look through monster loot more efficiently, collect and create salvage, and even buff yourself. It's highly customizable too, so you can choose exactly what monsters to look for or what loot to pick up. Quest Timer keeps track of ... your quest timers! When you pick up an Eater Jaw or kill the Harbinger, the plugin automatically writes down the date and tells you when you can do the quest again. Historically its author would add timers each patch, but he hasn't done that for some time. Fortunately, you can write your own timers as long as you know what item sets the timer and how long it is. Last and least (for most people, anyway), DCS gives you a specific name for the colors in a piece of loot-generated armor. It's really a vanity issue, but I like my Celdon veins to match!