I recently bought a new PDA, a Palm Tungsten T5, to replace my ancient Handspring Visor. Previously, I thought it was amazing that I could have a complete dictionary on my PDA. Now, I have the whole of Wikipedia, complete with most of the images!
I bought a 1 gb SD memory card, and plugged it into the T5. Then I downloaded a version of Wikipedia. It's in TomeRaider format so I had to download and register TomeRaider for Palm (it's shareware). (If anyone knows a completely free solution, or even better open source - let me know.)
At this point I ran into some problems with installing the Wikipedia file onto the Palm SD card. The Palm QuickInstall didn't like the .tr3 file so I used Drive Mode to copy the file. It took about 30 minutes to transfer the 1 gb file but TomeRaider on the Palm didn't show the new file. I thought the problem might be that I hadn't put the file in the right directory so I tried to move it, but that didn't work because it ran out of space - apparently to move files it makes a copy. The Documentation mentioned something about Palm not recognizing .tr3 files so you had to rename them to .pdb - I tried this, but it still didn't work.
A Google search turned up a page where it said simple renaming didn't work - you had to open the file with TomeRaider for Windows and then use File > Transfer to Palm and then HotSync. I tried this but HotSync didn't transfer the file. And QuickInstall didn't show the file either. Looking at the directories, I saw TomeRaider had put it in the CardInst directory rather than the QuickInstall directory. I dragged the file to the QuickInstall Expansion Card pane (which put it in the QuickInstall/ExpCard directory). This time when I HotSync'ed it started to transfer the file.
Sadly, after about 40 minutes, for some reason HotSync lost connection and didn't finish transferring the file. But at least I could see that it was trying to put it in the Palm/Launcher directory on the card. (Later I found this directory is a setting in TomeRaider.) So I tried again using Palm File Transfer. This time the transfer succeeded.
Voila, Wikipedia on the Palm! I don't actually have a practical purpose for this, it just seems like an amazing thing - to have an encyclopedia in your pocket. So whatever comes to mind, you can look it up. And the fact that's it's the Wikipedia encyclopedia makes it all the more amazing. 750,000 articles (in English) and counting - all freely contributed! It's an amazing feat. Unfortunately, the file I downloaded was created before I added the Wikipedia entry for Suneido :-(