I'm, personally, not big on sand ceremonies or unity candles, so we didn't do it for ours, but I've been to plenty that had them, and it made the bride and groom happy.
One thing I've heard of/read about (but never seen in person) that I think is cool is a wine box ceremony. If we had had a more secular ceremony (ours was in the church I grew up in), I think I would've thought more seriously about trying to incorporate it.
Basically, during the ceremony, you place a bottle of wine in a box with letters to one another commemorate the day (then nail the box shut or lock it or something). You open the box on a designated anniversary, read the letters, and drink the wine. You may also open the box if you're in a bad place and considering separating...to remind you why you were married in the first place.
I'm sure searching online you could find good suggestions for what should be read by your officiant/friend during the ceremony.