Since 1.4 Krita allows colors to be managed, in KOffice2 all applications allow color management. Why is the usage of this technique useful and what does it actually do?
There are other places which explain this very well, so here a list of external sites; Color Management intro lists technical background, why to do it and technical info like rendering intents. Wikipedia has also provides an introduction to color management.
The most common profiles are the profiles defined by the International Color Consortium, theire website provides a lot of information about color management, like the full specification of the profiles or technical notes and informations about profiles.
This application seems to have various interresting ideas; Gamutvision. Especially useful on that page is the 'Profile downloads' section which links to printer manufacturers and ICC profile providers. iccexamin is an application which allow the visualisation of icc profiles.