it's pretty terrible for word of mouth marketing on top of what benjamin said.

surviva - "hey check out my website, procrastinaters.com!"
friend - "cool, i will!"
surviva - "just make sure you spell it wrong, er instead of or!"

there are sites that "play on words" or have misspellings in their urls and do just fine because it's intentional and relates to something. is the only reason you misspelled the word because procrastinators.com was already taken?

you could be more creative like procrastinatorscentral.com or heywhatsupimaprocrastinator.com.