Playstation 3 IP's worth trying?

Hey all
 
After completing Uncharted 2: Among Thieves today I am finding myself considering looking into other Playstation games. I would like suggestions on any IP's I should try on there that meet the following criteria:
 
1). Are mainstream gamer friendly - I would consider myself a mainstream gamer as I like shorter titles that keep me entertained and are not overly challenging (i.e. they are not a simple walk in the park but I dont need ninja like skills to finish such as Ninja Gaiden)
 
2). Excellent game mechanics - the game should be really well made and not feel a quick 2 minute throw together.
 
So essentially games that are well made, and reasonable lenght to keep me occupied (so not a 100 hour game as I wouldnt finish it).
 
Also, as a side question, what do the wepon unlocks in the Uncharted 2 game store do? Do they give you those guns automatically in single player and are they unlimited ammo? How do you choose which to use if thats the case?
 
Thanks all :)

inFAMOUS
Killzone 2
Metal Gear Solid 4
Uncharted: Drake Fortune (1st Uncharted game)
Gran Turismo 5
Resistance 1 & 2
Batman: Arkham Asylum (not strictly an exclusive but you get the bonus of playing as the Joker if you buy the PS3 version)
 
That's just a handful I can think of atm!

Well, since Hamz put up a really good list I'm just going to add Valkyria Chronicles, which you should definitely check out if you're in the mood for a Japanese game. It's a strategy rpg with action elements, and it's not super long like a lot of other jrpgs. Also it's worth noting that it's a beautiful game, not in the same way Uncharted 2 is, but it's very stylish. Last thing to mention is the gameplay which, when you get used to it, is tons of fun.

I'd recommend Infamous first because it's just straight up awesome, and gets better and better as you play.

how come no mentioned this one mentioned so far: 

• Ratchet And Clank Future: Tools of Destructions .

• Ratchet And Clank Future:   A Crank in Time.   
• God of War Collection (in case you missed out on God of War on the PS2)
• Heavy Rain
• The Last Guardian 
• God of War III

excuse me, but what the hell is an IP?  
i always hear about it, but i actually never knew what it was :(  
*hides in corner* 

" excuse me, but what the hell is an IP?  i always hear about it, but i actually never knew what it was :(  *hides in corner*  "

inFamous and Killzone 2 are interesting choices, I may have a look into them.
 
I am also interested in Batman and Ratchet and Clank, how do they fit into what I have put?
 
Same for Wipeout HD?

Heavenly Sword was an interesting - if short - game. The cutscenes were rather cinematic and really well put together. It gets a bit tricky in spots, but not Ninja Gaiden difficult, and you can change it to easy i think. It's worth checking out if you can find it for cheap.

On the downloadable front, I am having a lot of fun right now with Mushroom Wars.
 
Fat Princess is also pretty fun.

Since no one has mentioned them yet:
  
Motorstorm / Motorstorm: Pacific Rift 
LittleBigPlanet

Id definently say to start with InFamous, skip Metal Gear Solid 4 and Killzone 2, both are overrated and not very mainstream gamer friendly in my opinion.  If you want a shooter I would suggest Resistance 2 over these.  Heavenly Sword is a great suggestions also.  So those are probably the 3 best Intellectual Properties exclusive to PS3.

Isn't "games" a better term to use in this case, as opposed to "IP's"?

Well I put IP's as I ment series rather than just singular games (i.e. is the Killzone franchise worth trying or Wipeout etc)
 
Also does anybody have any ideas about my Uncharted 2 question as I have been searching online and nothing seems to come up as to what the wepon unlocks actually do.
 
Thank you to all those who have suggested games, I will have a look into them and see what the reviews are like, prices, and whether or not they hit the "hmm that looks cool" note with me or not. I appriciate your help to those who have done so :)

Killzone 2.
LittleBigPlanet.
Resistance 1 & 2.
Wipeout HD - definitely.
Ratchet & Clank.
Siren: Blood Curse (if you like horror, I think this is pretty good).
God Of War Collection - get a preorder in for a history lesson in last generation's best Playstation franchise.
Pixeljunk games.
Motorstorm: Pacific Rift.
inFamous.
Metal Gear Solid.
 
Plenty there to get you going; my biggest recommendations would be Ratchet & Clank and Wipeout personally -- but that's just because they are my favourites.

I'm not positive but I think the unlockable weapon menu in Uncharted 2 allows you to pull that weapon with full ammo from thin air anytime you want. I can't test this right now since I'm doing a hard playthrough to unlock crushing and it (understandably) doesn't allow you to use tweaks on difficulties you haven't beaten yet.

" Well I put IP's as I ment series rather than just singular games (i.e. is the Killzone franchise worth trying or Wipeout etc)  Also does anybody have any ideas about my Uncharted 2 question as I have been searching online and nothing seems to come up as to what the wepon unlocks actually do.  Thank you to all those who have suggested games, I will have a look into them and see what the reviews are like, prices, and whether or not they hit the "hmm that looks cool" note with me or not. I appriciate your help to those who have done so :) "

Ah cool, so you can only use it on a already completed difficulty? Thats a shame as I was going to try hard with a random assortment of wepons (grenade launcher and unlmited ammo for the win).

InFamous!!!!!!!! AWSOME GAME!!!!!!