If I understand your question well, you have a datetime field and you only want the time as a default value?? Why not do a time field and when you insert a record in your table you just put now() as the data instead of NULL or something else. Here's what i would do :
create table tablename(
fieldname TIME NOT NULL,
and when you insert :
insert into tablename values(now(), data, data, data...);
If you are using VB you could just do a Sub and leave the now() always there since it never changes
mythix, you're not doing anything wrong, mysql doesn't support what you want to do:
"A DEFAULT value has to be a constant,
it cannot be a function or an expression."
you could use a TIMESTAMP instead:
"A TIMESTAMP column is useful for recording the
date and time of an INSERT or UPDATE operation
because it is automatically set to the date and time
of the most recent operation if you don't give it a
value yourself. You can also set it to the current date
and time by assigning it a NULL value. "