Galaxy S3 suggestions.(Or Android in general)

widget locker, titanium backup (you gotta root for this), then freeze all those useless telcos, samsung bloatware. I should know, I am using an s2.

Use it to prop up your coffee table. Oh you mean the Galaxy....

Download golauncher.

here

Root it, flash CM10 or AOKP, and then run Apex Launcher.

Well I haven't rooted, and here's a list of apps I recommend based on that:
Astro File Manager, Dolphin Browser (and Dolphin Jetpack addon), Google Drive, Dropbox, IMO, Gmote, My Boy! Free (gameboy advanced emulator), Play Music (if you use google music. If you don't: start), Where's My Droid, Yellowbook. Also don't use the bullshit Navigator Deluxe GPS they include, use the Google Navigator, as it is 10000 times better. There's probably more that I use, but those are the cool ones. Oh and don't forget to go nuts on the Live Wallpapers, I use Galaxy Core, but there are tons of cool ones.

For a start - Enjoy it as it is. Don't mod it right when you get it.

ADW launcher is great. Or root it and put there some custom rome .. like CyanogenMod. apps... I personally really like Shush! . it's handy and it should've been in the default phone (everytime you set your phone to mute/vibrations, it asks for how long you want to mute the phone, and then it automatically gets back to the normal settings, great when you are forgetting about turning your phone again after appointments and stuff :3

I bought an S3 some weeks ago for a trip so I haven't really been tinkering with it. But I LOOOOOVE it and like people say, use the vanilla stuff for a few days to get used to the UI.

I'd recommend XDA Dev and also checking out Godprobes' post. I have to skim through that myself and check all the links out!

Go root it and install CyanogenMod! It's really good imo :0

I suggest taking a look at the Nexus 4 as well. Excellent specs for around two-thirds of an S3 unlocked. I ordered mine today!

just make a good backup and then have fun exploring your new phone knowing that is shit goes wrong you can always fastboot load your stock .imgs and your back up and running

also look up cifs if your lucky someone has compile the modules for your phone and then you can mount windows shares as if they wore on your phone... That means you can listen to all your mp3s and videos without having to download anything this is super cool for tablet

Dont get the S3, the S2 is cheaper and its one of the best mobile phones in my opinion (i have it), You can root it by yourself with 4 or 5 easy steps (i did it with mine) and it is excellent, i dont have time to write a detailed post now, but i will do when i get back home :)
Edit: I wouldnt change my S2 for an S3.

Dont forget to get the Amazon App store. They give a paid app for free every week. Once you download it its linked tot you account forever.

I just bought the S3, and the phone is amazing, you will not be dissapointed

EMULATORS!!

nesoid

N64oid - Did someone say Zelda and star fox on your S3?

SNeoid (couldn't get to work, using SuperGNES)

GameBoid

ePSXe - I was playing FF7 today, it works perfectly

Othergames: GTA3(VC soon), Jetpack joyride, Plants vs zombiees, Humble Bundle)

Apps: Soundhound, Chrome, steam