From PCWorld.com:

1. America Online (1989-2006)
2. RealNetworks RealPlayer (1999)
3. Syncronys SoftRAM (1995)
4. Microsoft Windows Millennium (2000)
5. Sony BMG Music CDs (2005)
6. Disney The Lion King CD-ROM (1994)
7. Microsoft Bob (1995)
8. Microsoft Internet Explorer 6 (2001)
9. Pressplay and Musicnet (2002)
10. dBASE IV (1988)
11. Priceline Groceries and Gas (2000)
12. PointCast (1996)
13. IBM PCjr. (1984)
14. Gateway 2000 10th Anniversary PC (1995)
15. Iomega Zip Drive (1998)
16. Comet Cursor (1997)
17. Apple Macintosh Portable (1989)
18. IBM Deskstar 75GXP (2000)
19. OQO Model 1 (2004)
20. CueCat (2000)
21. Eyetop Wearable DVD Player (2004)
22. Apple Pippin @World (1996)
23. Free PCs (1999)
24. DigiScents iSmell (2001)
25. Sharp RD3D Notebook (2004)

Some of these were just painful to use. I've actually used a lot of these. Worthy list.