I've looked at a few of the new WebOS applications and like what I've seen so far. My favorites:
Google Maps, which comes preloaded on the Pre, integrates WebOS's Universal Search feature quite well. You can access Google Maps from the home screen by typing your location. Universal Search will initially list results from your contacts and apps and then give you the option to search Google Maps (you can also search Google, Twitter and Wikipedia). You can also take advantage of the Pre's multitasking capabilities by running your calendar and Maps simultaneously. I found this incredibly helpful for scheduling my weekend: I could make plans with friends, put them in my calendar and then search for locations without closing out of either app.
A YouTube app comes installed on the Pre as well. You can search all videos by simply typing, or you can view the most popular or highly rated videos from the provided lists. The Pre always displays the videos in landscape mode and delivers them in H.264 format, regardless of whether you connected over Wi-Fi or EvDO. You can't comment or rate videos, however--an annoying omission.
Fandango and Pandora, both of which are available from the App Catalog, were definitely my favorites among the dozen or so apps I looked at--because of how they integrated with WebOS. Fandango uses the Pre's location-based services to find theaters in your area. You can also watch movie trailers, buy tickets, and add showtimes to your calendar--again without having to close the app.
Meanwhile, Pandora capitalizes on the Pre's multitasking capabilities by running discreetly in the background while you use other apps. Song and artist titles appear in the Notifications area, so you don't have to reopen the app to figure out what you're listening to. You can also pause and give thumbs up/thumbs down judgments from Notifcations. If you want to skip a song, just tap the 'P' in the bottom corner of your screen to pull up the app.
Palm OS Apps Work on Pre
The lack of WebOS apps at launch is admittedly disappointing. Palm says that many older Palm OS apps will work on the Pre (though, clearly, they won't take advantage of the new hardware and software). To use the older apps, you'll have to download MotionApps Classic app, a Palm OS simulator that runs in WebOS; fortunately this app is available at launch.