Look-up fields - not in drop-down form?

Look-up fields - not in drop-down form?

Hi,
 
When linking two forms with look-up fields, is there a way for the user to enter an answer in  the look-up field in Form 2, rather than selecting from a drop-down which was populated from answers from Form 1? After a while the drop-down list gets very long and messy looking.
 
Thanks,
 
Elizabeth