readied actions?

[Zeofar]

when i reveiwed it on the srd it seemed almost like "if you guess what the enemy does, you get to go first in the initiative line"

As stated, it is an interrupt (You can do a non-interrupt readied action, but you might as well delay your action if that's your intent), not a guess and win a bonus thing. You don't "get to go first in the initiative line"; you actually decrease your initiative unless you lose almost a whole turn rotation.