How can I remove glue remains from labels on tins you want to use for decoration?

I usually soak tins or glass jars in hot water and then use a scrubber after they've been soaking for a while. Sometimes, depending on the label it needs to soak for quite a while (say, an hour). I've also heard that peanut butter can help get those off, by rubbing the peanut butter in and then scrubbing it all off. Sometimes oils like that can get in under the glue and separate the glue from the surface.