What do your sibling/in-law want or need? I don't think most people today expect much tangible assistance from godparents, because all of the formal rights and responsibilities of godparents have been removed or fallen into desuetude. Hell, in the modern rite of baptism you don't even answer the questions. It's treated as mostly surplusage, which is unfortunate. If I were being asked to be a godparent, I would request that the child be baptized in the old rite, which reflects the importance of the job and gives the godparent something to do.
The first thing you should do, though, is smack the kid's parents for waiting until she is a year old to have her baptized. That's irresponsible. (I assume they aren't just now converting from some non-Christian or credo-baptizing background.)
The best gift for a godchild is the one recommended by Hillaire Belloc: a pipe of port, which will come of age at the same time as the child and last for many years thereafter.
But given that I don't know how one buys a pipe of port anymore, much less where the average American would keep it if you did, you might consider crucifixes and rosaries, which are common gifts. Get something that will last the child into adulthood, not one of those sickening pink things that is made just to be a nursery decoration. Perhaps consider a St. Benedict crucifix; they're fun and can be found easily around the internet.
For some reason both of my brothers have waited until their kids were about a year in age before having them baptized.
I had never heard of the pipe of port tradition, but apparently a pipe is approximately 500L. Maybe a nice bottle would suffice as part of the gift. I appreciate tradition, so would enjoy doing something with special meaning.
My wife would like to get her aquamarine earrings. Aquamarine is her birthstone and also the stone for the month she will be baptized, hence the year of age at baptism.
I think the "pipe of port" thing is from when you could easily buy wine before it was bottled. I don't think that's really possible for most people anymore.
If you get a bottle, be sure it's "vintage" port, which is the only kind that is meant to age.
Luckily I have 2 Godsons so I was able to take care of a few people that made the shit-list in between.
He will know what to do without even being told