If she's using alot of flowers for decorations/centerpieces, maybe you could put those together? I'm just saying that because I'm planning to DIY all my flowers (bouquets and everything). I'm going to purchase silk flowers in bulk off eBay and put everything together myself which will probably cost me about $150-200 at the absolute most instead of paying a florist thousands!!! Maybe you could offer to pay for some of the flowers and put them all together (no extravagant charges for labor!) for her.
Also, since I see you're a scrapbooking guru - maybe you could make centerpieces with the couple's photos in them? Or make them a really great scrapbook they can set out on a table near the entrance that has the guest book on it...