Lemon cake recipe?
There's a really good Lemonade Layer Cake on the Cooking Light site, it's really lemony because it has lemonade concentrate as an ingredient. I think the icing is made with cream cheese, it's also very good.
I'd provide a link but for some reason I can't access the Cooking Light site right now.
Most of the cakes I've seen are using a lemon icing, but here is a very simple Lemon Cream Frosting:
The cake recipe is made in a loaf pan, don't know if that will matter to you.
If you need any help post back here.
No matter what - I think it is so nice that you are willing to attempt making a cake for your wife. Hope she has a nice birthday.