"My guy's birthday is in a month and I'm trying to plan ahead so I can make it amazing and unforgettable. What is something unique, fun and still romantic that we can do?"
The most important thing to remember is that what makes a gift cute, romantic and unique is that it is special to both of you. Sometimes it can be as simple as surprising your man by taking him somewhere where there was a failed date, where you first met or where something embarrassing happened. In fact, surprises are often the best way to make a birthday memorable. Make him think he's putting up with an errand and than take him somewhere awesome. The best way to make this surprise work is by making it seem like you're on the way to his birthday dinner or something like that, but you "just have to drop off a letter of recommendation form at someone's house real quick." It's easy to see through a surprise where it seems unnatural, so don't ignore the fact that you're doing something for his birthday; he'll see through that. As for what you can do, something out of the blue that he would never expect makes it unforgettable, drive somewhere and shock him by going skinny dipping, have a willing friend serenade you at dinner or set up a fancy table for two on a hike somewhere. Go for shock value, but make him realize that by making his birthday fun, you're enjoying it too. The day is about him, but he'll enjoy it way more when he sees that you're just as happy to be a part of his birthday as he is.