The news of the NGP kind of make me want to charge my psp and play some games on it. what games you guys recommend? if you can please give me your top 5 games.

Monster Hunter Portable 3rd, you'll have to import it or wait till it's release stateside though.
Metal Gear Solid Peace Walker.
Persona 3 Portable.
Final Fantasy 9 from PSN

I love Monster Hunter but that's not for everyone. The God of War games are very good. Lumines is awesome. Kingdom Hearts Birth by Sleep was good.  
 
Those are the only PSP games I can think of right now. I'll edit some more in when I think of them. 

Final Fantasy: War of the Lions 
Infected 
God of War: Chains of Olympus 
Dungeon Siege: Throne of Agony 
Syphon Filter: Logan's Shadow

Wow lots of RPGs, do you guys know any rpg that is similar or close to fallout or mass effect?

Persona 3
MGS Peace Walker
Both GOW games
Dungeon Siege

" Wow lots of RPGs, do you guys know any rpg that is similar or close to fallout or mass effect? "

I haven't play any Jrpgs in my life, and most of psp games are Jrpgs. own the 2 Gow games and some puzzles games.... im kind of looking for that game that make me play it non stop.

So far...

Daxter
Street Fighter Alpha 3 MAX
WipEout Pure
Grand Theft auto: Chinatown Wars
God of War: Ghost of Sparta
Resistance: Retribution

Thanks for all the recommendation guys im going  to watch some gameplay videos of each game and then decide,, now the only problem is to find it on the playstation store (NGP compartible)

P3P is the only recent game that I've played on my PSP. It was really good though. I gotta get back to that second playthrough.

A few:
 
1.  Crisis Core
2.  Persona 3 Portable
3.  Kenkabancho Badass Rumble
4.  Ridge Racer 2
5.  Castlevania Dracula X Chronicles
6.  Mega Man Powered Up
7.  Mega Man X Maverick Hunter

Yup, hate to keep repeating games but  

Metal Gear Solid Peacewalker
Kingdom Hearts Birth by Sleep
Final Fantasy VII Crisis Core
Final Fantasy Dissidia
God Of War ones
 
They were all mad fun :P

1. Peace Walker 
2. Killzone Liberation 
3. Ghost of Sparta 
4. Lumines 
5. Chains of Olympus 
6. Crisis Core 
7. P3P 
8. Disgaea: Afternoon of Darkness 
9. Wipeout Pulse 
10. Patapon 2 
 
Damn, I forgot how many awesome games there were on the PSP.... and there's a bunch more coming out! 

What about "Lord of Arcana" ? also how is the camera in peace walker?

LittleBigPlanet PSP has stole away more time from me than I'd like to admit. Even if I own it on the PS3, the portable version is utterly great in its own ittle way. There's even a demo out on the PSN for it.

As long as theres Lumines I am happy.

1. Burnout Legends
2. Tekken: Dark Ressurection
3. Monster Hunter Freedom Unite
4. Lumines
5. Wipeout Pure

" Monster Hunter Portable 3rd, you'll have to import it or wait till it's release stateside though. Metal Gear Solid Peace Walker. Persona 3 Portable. Final Fantasy 9 from PSN "

Disgaea: Afternoon of Darkness is my favorite psp game. It's really great.