Any DIYer will tell you how important a good level can be. From accurately hanging pictures to checking the alignment of doors and windows with the rest of a building, levels are an indispensable tool. But there's only so much a bubble or a simple pendulum can tell you, which is why laser levels have become so popular. They can do everything a standard level can do, only better. Yes, most laser levels still rely on the old technology, but reading one is as easy as looking for a beam of red light.
Basic laser levels are fairly inexpensive (between $15 and $100), but if your DIYer could use it, you may want to consider investing in a self-leveling unit that needs little input or adjustment. Self-leveling units save time are more reliable that standard levels, though they cost anywhere from $100 to $1,000.