Apart from the NEC Multisync 3D, there is also the older Multisync II. Avoid the Multisync 2A, since it won't sync all the way down.
NEC's main contender is Eizo, who have made one or two multisync monitors, in the Flexscan range.
Idek Iiyama has also made a range of multisync monitors, of which I've got the 21" version.
Telenova is a rebadged Mitsubishi which will at least handle 15 KHz in digital colour.
IMP is another brand of which some models are Amiga compatible.
TV-capable Nokia monitors will also handle 15 KHz.
