What should I Gift to my husband on his Birthday?  

Wow, pretty broad question you ask here. I don't know your husband so I couldn't even begin to suggest a specific gift. I can give you some advice to narrow it down a little bit though.
Men are simple creatures, we like practicle usefull gifts, rather than token or symbolic things. Tools, electronics, even simple clothing. The best way to find out what he wants, is simply to ask. Like I said, men are simple creatures, we are direct and to the point, just ask us what we want and we will probably be glad to tell you. Does he have a hobby he engages in frequently? Perhaps something to do with that would be good. If you don't know mch about it, again, ask him, or if you don't want to ask him, ask someone who knows him well and knows about his particular hobby, they may be able to guide you in selecting something specific.

Zero in on your husband's interests or hobbies. You can get ideas from it. You are the one person who knows your husband inside and out.

I can only suggest a good site where you can find the best gift idea, http://www.gifti.us