OP updated 6/7/2012

Well, I started a thread  back in August (http://forums.joeuser.com/411269/) that's seen a lot of activity and actually had quite a few good bits of information for new and old players alike.  I figure it's time to start a new thread and perhaps keep the OP up-to-date with useful information, etc.  Feel free to use this post for any LoL discussion, etc.

Super fast background:  I played a lot of Demigod as pacov/cheesuscrust.  Back in August 2011 or so, I started getting heavily involved in LoL and folks have been kind enough to chime in with tips and links to various sites that have been quite useful to me.  In addition, I've been able to keep up with folks that I've played Demigod with in the past and meet some new folks that play LoL and frequent these message boards. 

Here's some of the things I've learned in the previous thread:

• Added 12/5/2011:  For anyone that is level 30 with an account in good standing, you can participate in the tribunal.  This is a system that was setup by riot to allow the community to police their own.  In short, you get to review cases where players have been reported and recommend that a player is forgiven or punished for their behavior.  Check it out here:  http://na.leagueoflegends.com/Tribunal
• You can view players stats here:  http://www.lolstatistics.com/ (thanks darkliath!) - this is a useful way to get info on your previous matches and to look up players if you like
• You can often find some great live streams here:  http://www.mobafire.com/league-of-legends/stream/ .  Watching good players as they pug or play with teammates helps me learn the best.  I highly recommended firing up some of these streams and watching some of the top players go at it.  Great learning tool.  
• You can save your replays and view them whenever you like or upload them. Go here to get the necessary software:  http://www.leaguereplays.com/download/ and then go here for more info on how it works:  http://leagueofreplays.com/faq.php .  Took me about 3 minutes to figure out and setup.  Very simple and then you always have a small replay file (2-5 megs) including all the details from your game (items/kills, etc - and you even see all of the in game chat).  This also makes it MUCH easier to go back and watch how another person plays if they did a great job or figure out where you messed up and then improve.
• Sites that are great for player build guides, etc: www.solomid.net and www.mobafire.com
• An excellent site with guides and up-to-date info on one of the better competative teams, CLG:  www.clgaming.net
• Folks from DG that play LoL - pacov, zex, zen_god, jona, thundercles, hedgie, trouser, orcun, mith, misterhankey, morpheas, mcshane, darkliath - probably quite a few more that I can't think of at the moment
• Added 12/5/2011:  You can get a free unchained alistar skin - this also gives you the character for free as well.  See here:  http://www.neoseeker.com/forums/45610/t1685348-free-unchained-alistar-skin/
• Added 06/7/2012:  You can get the riot girl Tristana skin for free by following Riot's youtube channel.  This also unlocks the character for you.

New Player tips

• Play the tutorial.  Seriously.  Play the tutorial.
• Riot gives you some RP after you play your first game or so.  It's enough to buy some skins, a boost, or a cheap character.  You'll typically notice this a little after you play your first game.
• Learn to last hit!  Last hitting is simply landing the last hit on creeps.  If you last hit, you get gold for that kill.  You will need to learn when you should push a lane and when you should just last hit (this means DO NOT attack the creep wave, just let the creeps fight each other and then snag a last hit whenever possible) - the number of creeps you have killed is tracked in a value called CS.  You can see that number at any time by pressing tab
• Added 06/07/2012 - Sometimes its good to do some damage on a tower.  Sometimes not so much.  Understanding the difference is huge.  For instance, if you manage to kill one or two of the enemies and there is no one in the lane, consider pushing your creep wave to the tower and retreating.  Any creep that dies to the tower is experience and gold that you have denied the enemy.  Doing this right gives you an advantage and ensures the creeps are in a good spot when you come back from the shop.
• Read some guides on any character you want to try out.  The recommended builds (what you see when you go to a shop) are not optimal.  The guides include item suggestions and skill orders.  These are very useful in learning decent ways to build characters
• Added 12/5/2011:  So, you know you can't get level 3 runes until you hit level 20?  Well, guess what - that's not entirely true.  Hedgie came up with a way to get level 3 runes at any point.  The bad news, its random.  Here's what you do.  You will need 375 IP.  Buy any tier 1 rune that costs 15 IP.  You need to purchase 25 of these.  Click on your rune page.  In the bottom right hand corner there is a button called the Rune Combiner.  If you place 5 runes in there, you can get a random rune that is 1 tier higher (eg if you have 5 tier 1 runes, you will get 1 random tier 2 rune.  Anyway, the math works out such that you spend 375 IP ( buy 25 tier 1 15 IP runes) and you get 1 completely random tier 3 rune.  Some of the quintessences are 2k IP, so if you luck out and get one of those, you just won the lottery.  Anyway, its not the best system as its completely random, but it does work and does give you a chance to get tier 3 runes at any time.  Another thing to consider, you can always keep the random tier 2 rune if it happens you ended up with a good deal or got something you need.  Going that route, you spend 375 IP and would have 5 random tier 2 runes.  That's fairly cost effective for 375 IP.
• Added 12/5/2011:  Consider saving IP for when you hit level 30.  Having tier 3 runes is a reasonable advantage.  If you don't save now, I guarantee you are going to be a little sorry when you hit level 30 and spend all your time slowly unlocking runes.

If you can think of anything else that would be good to add to the OP, let me know.  Thanks!

Great site I visit every day for LoL related news - http://www.reddit.com/r/leagueoflegends