I'll throw out a situation for you: a few days ago I picked my DS up from school, and as we were pulling away a group of 4 girls waved to him. <blush, blush> As he turned beet red, I asked who the girls were. His answer was: Maggie, Maggie, Maddie, and Maddie.
DS is 12. These girls are all in his class of 21 kids. Margaret was nowhere in the top 100 for girls the year he was born, but he has 2 of them in his class (he transferred schools this year, and he had had two in his previous class, too.). The other two are named Madison and Madeline; those names WERE in the Top 100 in 1997.
The moral of this story is, pay attention to where you are when it comes to the popularity issue if it is important to you, because the nicknames can trip you up. I live in a very Catholic community where the majority ethnic groups are Irish, German, and Italian. We have what seem like endless permutations of Katie, Molly, Maggie, Ella and Bella. These can come about in unexpected ways: for instance, a neighbor child is known as Molly, but her name is Amalie. (It's a German name in this case, pron. ah-MAHL-yuh. If the person is French, however, it's ah-meh-LEE, with an "e" in the middle instead of an "a".)
Which brings me to the other point I wish to bring up: when spelling ethnic names correctly for their languages, be aware that people WILL decide that the name is properly spelled or pronounced a different way if they know a similar-looking or similar-sounding name from another language, because "it's the same thing." You need to look realistically at whether or not that is going to drive you batty. After two years I have gotten to the point that I can ignore most of the people who call my daughter Ashley, though I'm afraid it still grates on my nerves to hear her called that.