PSP's widescreen is screaming for a new Klonoa game. I am also really looking forward to the Gradius 1-Gaiden collection and the Capcom Collection remix (for 1941, Varth and Strider).
My current portable time is divided between:
DS/GBA: Mario Kart DS on and offline and Gunstar Super Heroes (trying to beat on hard with Blue)
PSP: Tokobot (one of the best platformers I have played in years), Burnout Legends, and Wipeout Pure (Delta Packs 1 and 2)
I just got a new 2 gig card and have it loaded with 3 new MST3Ks for my roadtrip this weekend and I downloaded fanjita's 2.0 eboot loader so I can play NESTER and Genesis even though my firmware is upgraded. Ya like that, Sony? Only problem is it's buggy as heck and freezes a lot but once the emu loads it's smooth as butter.
