Anniversary Ideas

My husband and I will be celebrating 15 years of marriage next month. Yay for us!! We don't normally celebrate big, but since this is a "milestone" I would like to do something more than usual. For our 10 year mark we purchased silver wedding bands while on vacation in the Bahamas. This time our finances are not like they were back then, so I need some low dollar but impressive gift ideas to think about and consider. So, can you help me come up with some ideas? I'd love to have you share with me your thoughts!