Unfortunately there is no reliable online resource for Japanese names that is user-friendly for an English speaker. One problem is that the number of potential names, and their potential meanings, is so vast that it's completely impractical to list them all. Most lists that you will find in English give only the most common names with their one or two most common meanings.
The online dictionary ENAMDICT is excellent for looking up kanji spellings of Japanese names, but it doesn't give definitions of the kanji in English. You would need to look up each kanji separately, and that's quite laborious. If you would like to take a look, the link is
http://www.csse.monash.edu.au/~jwb/cgi-bin/wwwjdic.cgi?1E . Select "Japanese names (ENAMDICT)" from the drop-down box labeled "Dictionary." You then type a name, such as
Karen, in the Keyword box and will get a list of kanji spellings.
From there, you can copy the characters and look them up in the Kanji Lookup section. But as I said, it's laborious, and there are about 100 spellings given for this one name alone. From the point of view of an English-speaker looking for a name with a particular meaning, it's much easier to ask a Japanese-speaker to suggest names that might incorporate that meaning.
I'm sorry I can't be more helpful! If a particular name that you've seen or heard appeals to you and you'd like to know its meanings, or if there are particular meanings that you'd like to incorporate together, I might be able to help with that. Or maybe someone else here knows of a resource better than the one I've mentioned.