Any of the suggestions Ed or I gave would work with lamb as well.
I don't advise getting too adventurous with new recipes when you have guests coming. But here are some ideas to play with. Maybe make a bit of stuffing for chicken and see if you like it before committing to a an expensive leg of lamb and a dinner party. You could go Moroccan, Middle Eastern, or Greek. These aren't recipes I've tried, but I thought they look good. Two of the recipes are actually for other cuts of lamb. So don't use the cooking technique given. I just linked them for the stuffing ideas.
http://www.theguardian.com/lifeandstyle/2010/nov/14/recipe-stuffed-breast-lamb-lebanese (the recipe is WAY down at the bottom)
(PS- The Moroccan calls for "ras-el-hanout." It's a spice mixture containing the spices already called for in the recipe plus clove cinnamon and nutmeg. You can leave it out and just add a dash of those.)
You could serve these with the sides appropriate to the cuisine, but if that's too daunting, roasted root vegetables and a green salad or marinated mixed vegetables would work.
You can make stuffing with whatever sounds good and you have on hand. Break down the stuffing components and you get
vegetables- onions, carrots, celery, garlic, spinach, mushrooms,etc
herbs and spices
other flavors- nuts, cheese, fruits, olives, marinated artichoke hearts, etc
starch- dry bread crumbs moistened or fresh ones, prepared rice, maybe others?
You can add flavor by choosing different moistening liquids, milk, wine, broth or fruit juice.
Toast any nuts and remove from pan. Saute the vegetables, with spices adding any fresh delicate herbs at the end. Then add any additional ingredients and the starch. (If your pan is big enough, you can mix it all in there. Mix gently so your starch doesn't get gooey) Keep in mind both the vegetables and meat will add some moisture to the stuffing, so you don't want it too wet..You can add a bit more dry bread crumbs if it is. This was the biggest challenge for me. But after you prepare it using a good recipe a few times you'll get the feel for how moist it should be.
Most important when trying a new recipe!! Taste the stuffing and make sure you like it. Maybe only use half the herbs and spices if you are uncertain about the flavors. You can always add the rest if it needs more. If it's too strong add more starch. Keep in mind that you're not eating a big bowl of the stuffing by itself though. It should be very flavorful, you want it to be noticed.
Whew! I think I've now told you everything I can think of about stuffing! Have fun!