This is a good idea. I have a laser level, but it only projects laser chalk lines, it doesn't have beam that projects a single point. I wasn't aware that these things were available. This would seem to be a great and cheap alternative to the the products that are marketed specifically for enlarger alignment. (don't want to mention specific products)
I'm wondering if this one might work:
I noticed that some of the products that might seem to work say that they are "self-leveling". Obviously, unless the baseboard was perfectly level, this would only complicate the matter.
Thanks mattk for mentioning this.
In response to others' questions about using this sort of device:
The idea is to project the beam from the baseboard up to a reflective surface (mirror or glass) where the negative would be. The beam is reflected back, and if the two surfaces (negative plane and baseboard plane) are not parallel, then the reflected dot will not be in the same position as its source. The adjustments can then proceed. If my understanding of this process is not fully correct, or there is more subtlety than I understand, I hope the masses will chime in.