Mo's Digital Pencil Groom's Shoes – brilliant illustration and accompanying sentiment!
KPM Doodles Wedding Digital Stamps – this one's great for all kinds of weddings. For a same sex wedding I like that there are more than one type of bride/groom shown. Use two grooms or two brides and the wedding cake and there you go.
Miss Tina Wedding Doodles – again, all the elements you need for any kind of wedding.
Pixel Scrapper Wedding Words Kit #2 – sign up with Pixel Scrapper and you can get this fantastic sentiment kit for free.
Just Inklined Just Married Grooms – the perfect stamp for men!
Just Inklined Digital Stamp Bows – another great one for the guys.
Just Inklined Just Married Brides – the perfect stamp for women!
Digital Delights Toasting Bears – not a wedding card per say, but this would work very well for men.
Free Craft Downloads Same Sex Marriage Digi Stamps – some cute freebies for you.
Sliekje Digi Stamps – Angelique has quite a few free digital stamps that will work well for same sex weddings. In addition to the couples – Wedding, Engagement, Relationships stamps – she has several other cute images that would work splendidly, such as the cute love birds Spring Time stamps!