Top ten words I constantly forget the proper spelling for:
10. Austrailia or Australia
9. Prision or Prison
8. Almighty or Allmighty
7. Lose or Loose (two different words I often but not always forget which is which)
6. Accidently or Accidentally
5. Apparrently, Apparantly, or Apparently
4. Incidently or Incidentally
3. Deadley or Deadly
2. Zeland or Zealand (as in Lew Zealand)
1. Desert or Dessert (I know these are different words, but I keep forgetting which spelling is for which word/pronunciation)
On a similar note, there's one Sesame Street animation insert that I constantly forget the title of. Is it "Eleven Cheer" or "Cheer Eleven"?
and here's the top ten Muppet character names that I used to have trouble remembering the correct spelling of (but have since been able to remember better than I currently do for Lew Zealand... I checked The Muppets Character Encyclopedia for proper spelling on that one).
1. Beauregard (though it was "Boregard")
2. The Swedish Chef (thought it was "Sweedish")
3. Roosevelt Franklin (used to think it was "Rosevelt")
4. Marvin Suggs (thought it was "shuggs")
5. Seymour (thought it was "Seymore")
6. Lindbergh (thought it was Lindberg)
7. Zondra (thought it was spelled "Zhondra", sometimes I still make the mistake... Though Muppet Wiki notes three different spellings from different sources)
8. Barkley (sometimes I still think it's "Barkly")
9. Angus McGonagle (thought it was "McGonacle" or "McGonicle")
10. Camilla (thought it was "Camillia")
Incidentally, some of the first words I knew how to spell were Muppet-related, including "Muppets", "Kermit", and "Ernie".