SL mods?

I have actually been a resident of SL for almost a year now, but I now have a little more time on my hands and I really want to start getting into it and becoming more involved. From using applications and playing games in the past, I've learned that getting a hold of whatever useful mods may be available right away is one of the better ideas, but I am really unsure of how many are out there for SL if any at all. So, that is my question. Are there any good mods that one could download to improve SL in anyway? Any good sites? I realize that there is another forum discussion for websites, but please go ahead and throw those at me as well if you really feel like there are some really good ones out there. Thanks for reading.

Yep, right here:
http://wiki.secondlife.com/wiki/Open_Source_Portal