Here's a list of PalmOS 5 apps which include ARM native code:

HotSync
AeroPlayer
PocketTunes
RealPlayer
SplashPhoto
PicturePlus
AcidImage
zLib (compression lib)
LightNZip
AES (encryption lib)
mEncryptor
PilotMicroRace
XCade
RPN 3.10
Power48
cbasPad5
SoundScope5
yCPUBench

(the last 3 are mine: http://www.hotpaw.com/rhn/palm/ )