Law school student: Business cards are the perfect item. You could also give them a business card holder too. If they don't already have one, a briefcase is a necessary item. They won't look complete without it. For the ladies, a wardrobe is very necessary and if she doesn't have any professional clothes or suits, these would make great gifts for her. You could go shopping with her so that she can try them on and choose what she likes.
Lawyer: Items for the office such as inspirational pictures or quotes. A name plate would be nice that they can place on their desk. Any office supplies that aren't supplied by they company they work for would also be great to give. But more than anything, the one thing they need after passing the bar and starting a new job is clients. Offer to take a lawyer out to lunch and bring along two possible referral sources.
Paralegals and Assistants: many women work in this arena and a great go-to gift every woman will always enjoy is a spa gift certificate. There is nothing better to show how much you appreciate their hard work than an hour of relaxation. For male paralegals and assistants, restaurant gift certificates or sporting event tickets are also a great option.