Treo Apps
    Okay, they're not all Treo only but these apps have particular benefits for Treo users

• PDANet (Shareware $34)
  
• Volkeys (Shareware $5.99)
  
• Turn the volume switch on the Treo into a scroll button.  Very handy for one-handed operation of the Treo.
• Volume Rocker (Freeware)
  
• Graffiti Anywere (Freeware but takes donations)
• If you've never previously used Palms you might not miss this but the ability to enter text via Graffiti on the main screen is very convenient for not having to put down the stylus to use the keyboard.
• Barcode v13 (Freeware)
• TeksPhotos (Freeware)
  
• KeyCaps600 (Freeware)
• QSetApp (Freeware)

Palm Networking Apps

• PalmVNC 2.0 (Freeware with suggested €10.00 EUR donation)
• VNC software for the Palm
• EzFTP (Freeware)
• pssh (Freeware)
• TuSSH (Freeware)
• ptelnet (Freeware)
• Mergic Ping (Freeware)

Utilities

• FileZ (Freeware)
• PalmHandZipper (Shareware $9.99 or Freeware 'Lite' Version)
  

Fun Stuff

• Geek Sounds (Freeware)
• Space Trader (Freeware)
• iRogue (Freeware)
• Lemmings (Freeware)
  
• Agile Messenger (Freeware)