with a rich, warm dish like cheese fondue, you'll want something cool and crisp as a counterpoint.
try steamed green beans marinated in olive oil and balsamic vinegar, sprinkled with herbs of your choice and some salt - chill well.
also try just a classic green salad, with a light vinaigrette dressing and maybe some slivered toasted almonds, craisins, and canned mandarin orange segments. try girard's light champagne dressing, available at most grocery stores.
check out the melting pot menu for other salad ideas - they do a seasonal menu called the big night out that includes themed/well-matched items...a cheese fondue, a salad, a meat fondue, and a dessert fondue. read about their salads for further inspiration.
fondue is a super fun party idea - enjoy yourself!
personal experience eating fondue at home and at the melting pot!