I figure that this board needs a thread to describe the bizarre scanline #0, which starts much earlier than one would expect.
When exactly does it start anyway?
Check the gambatte project on sourceforge, sinamas (the author) has a ton of different test roms written. Unfortunately, a few of them fail on the DMG (due to the STAT bug, i.e. writing to STAT during modes 00 or 01 (I think) causes a stat interrupt to immediately fire; was fixed on cgb, and the tests depend on this behavior)), and some of them depend on the specific 'uninitialized', 'mostly but not all 0x00' state of the sram in the author's particular CGB.
But other than the stat bug issues, the timing ones are fine; just be sure they pass on a real DMG before testing your emu against them.
The test roms are in the SVN tree for the project.
LN