Artifacts

they also make nice decorations for your artifact page. xD

But seriously, yea, they`re used to make useful things.

Here are the "useful artifacts" to aim for

Major dinero (shaves off 3% of an empire`s credit....using 52 of em would wipe out 90% of their cash.....a nice way to get folks off the rich list if you detest them)

Historia (-40 turns......particularly nasty when used in groups of 20 on fast,normal, or slow server, and might even result in your target losing his c2 or c3 if he doesn`t have friends who can help him out)
Big Time Capsule (+100 turns....a good defense against that historia I just mentioned)
Small time capsule (+10 turns, useful when you just need those few extra turns to accomplish something)
Minor and Major barrera (shield against good and harmful artifacts.....lasts until the next refresh).

You gotta dig for artifacts at the "right time". See the artifacts site. You can ask off the chat thingy on the right if you wana know (can`t be bothered to fish it up right now).

artifacts have a large number of uses , however artifacts are rather large and complex area of the game so your best finding a guide to this area , these can be located on fan sites etc

but in general artifacts have numerous affects both good and bad on any target empire you want including yourself, and can be fused into different / better artifacts