CTMod is a collection of user interface mods for World of Warcraft, similar in scope to Cosmos. It is developed and maintained by Cide and TS, whom were the staff of the (now-defunct) website WoW.WarcraftStrategy.com. Its most notable difference from Cosmos is that CTMod is built completely by one small team of people, as opposed to using several different developers' mods. It is updated and improved regularly, and is very popular (especially the CT_RaidAssist addon). It is committed to working with the existing UI wherever possible instead of replacing it, and there is an ongoing interaction between CTMod's development team and the WoW developers. CTMod can boast that some features originally offered by CTMod have since been incorporated partially or fully into the main WoW program.
CTMod works by having a central core mod into which other mods can be added and removed, similar to web browser plug-ins. A user may have as many or as few components of CTMod beyond the main one installed as they like. Installing a component is as simple as loading the addon containing it, and uninstalling simply means not loading the addon anymore. Components automatically register their options and control buttons with the main CTMod interface, thus keeping all controls for CTMod in one central location.
Download and installation
Since version 1.64, CTMod has had its own website which provides, among other things, the ability to download the individual AddOn features desired. To install in this manner, select the parts of CTMod you desire from their website's page and then unzip the file you downloaded into your World of Warcraft\Interface\AddOns directory.
CTMod does not modify the FrameXML or involve any external programs and therefore cannot permanently screw up your WoW interface. The mod (or even individual pieces of it) may be removed cleanly by simply disabling that particular extension from the AddOns button on the Character Select screen or, to remove it permanently, deleting that addon's directory under World of Warcraft\Interface\AddOns. The main CT_MasterMod mod must be installed for most other CTMods to work (a notable exception is CT_RaidAssist, which can be run stand-alone from the other CTMods).
Cide and TS also work on another project named CTScreens, which is a database for uploading screenshots. This is free registration, but for a low number of screenshots. Should you want more, you can pay to have access, with two levels; "Epic" and "Legendary".
Previously, the CT Crew also maintained a site named CTProfiles, however, this was brought down in late spring, early summer. The site was used for custom profile; the user could create their own character and add their own choice of items to many different profiles. Cide and TS say that CTProfiles was brought down due to the fact that it was consuming too much of their time, which had originally been meant for the development of CTMod. UPDATE: CTProfiles has returned in Beta form.