[GalanDun]

also wondering if there is somewhere that all the hacks/mods have been collected. i am looking for something i cannot remember and also i want to know what tools i need to get started hacking.

[Xalphenos]

For hacks and mods look in the "rom hacks" section and for getting started look in the "getting started" section. Look to the left for both. Also, for tools in general, see the "utilities" section.

[Auryn]

HERE is somebody project to make a database of hack/translations.
For the starting, check out THIS

[KingMike]

This site generally archives relatively thorough, completed ROM hacks (that is, not those that only change a couple graphics).
(with the exception of those that solely fix bugs in the original games)

zophar.net used to be a good site that saved almost everything, but it really died down as the 2000s went on.
DataCrystal used to, until it merged with this site and the focus changed to more of a hacking notes repository.