1. The Scavenger Hunt: For this particular idea it is good to get a lot of people involved, including family, friends and maybe even businesses in the area. You'll want to give her clues that will progressively take her closer to her destination. As an added bonus have a rose waiting for her at each of the places so that by the time she gets the clue to come to you she will have a dozen roses.
2. The Presentation: It's pretty common to have the ring in the bottom of a glass of champagne or in the dessert but let's take some time to think a little differently. What does she like? Does she scrapbook? Then make a scrapbook about your relationship. If you do this around her anniversary she will just think you are being romantic, but on the last page you could have the ring attached.
3. Public Proposals: When at a ball game have people on the opposite side of the field hold up letters that spell out marry me, or have it put up on the jumbo-tron. Yes, it's true that this has been done, but it is still a treat to see her face when she suddenly realizes that it is her that the sign is talking about.
Whatever you decide just make sure that you keep it romantic and light. This is something that you will be talking about for years to come so relax, take your time, and make it a night to remember.