You don't have to register at all; in that case most people will more than likely give a monetary gift or gift cards to stores you like.

You can register on Amazon for things like electronics.

You can register for other types of non-traditional items; DH and I registered for wine, and one of my cousins registered at Sears for tools.

Don't totally discount registering for a few select household items, either. You don't have to go crazy and ask for all new furnishings, but it's always a treat to upgrade to new sheets, or maybe some nicer pots and pans...  

Good luck.   :)

We also lived together, had all the household items we needed, felt no need to "upgrade" to more stuff, etc., and definitely didn't want or need a wedding shower. 

We did need new everyday dishes, so I went to BB+B and registered for that and a few other items. 

When people asked my MOH what to get us, she told them we were saving up for a new living room set.  We got almost all cash gifts. 

I dislike the idea of a honeymoon registry because there are fees, service charges, what if you have to postpone the honeymoon, and why not just get good old cash.  Depends on where you live, some people think they are fine, in other areas, not so much. 

Best wishes! 

Even if you are living together, you should definitely still register.  I have worked in the registry business for almost three years and can tell you that if you do not register or register for only a few items, you will get items that you do not want, need, like and/or have room for.  Not all of your guests will just give money or a gift card, they want to feel like a- they are bringing an actual gift to the wedding/shower and b- that in 20 years, you will remember that they bought that item for you.  I know it sounds crazy but I see it on a daily basis.  Sooo a couple other posters had great ideas- update items that you already have that may be getting old and of need of replacement in the near future.  (Are you dishes missing pieces or chipped?  Are your towels worn?  Does your toaster keep shutting off?)  Upgrading items is also an idea, you may have a very basic cookware set now but if you will be cooking and entertaining more in the future, it will be something that you will want to register for.  Same with sheets, you may have basic sheets right now so put a nicer set on your registry.  You are picking out items for your future together so keep that in mind.  Also putting items away for the future is a great idea.  You may not have room at your place right now but your parents or in laws may not mind storing some items for you until you move into a larger space.  Registering someplace like Target or Walmart is great because you can put great electronic items (like your computer) on your registry.  Plus putting big items on your registry makes it easy for people going in on a gift for you. (coworkers, couple of aunts, ect doing a group gift)  Dont forget about giftware like frames and perhaps a vase or even your Wedding Toasting Flutes and dessert set!  Those are specials items that people love buying and if you do not give your guests an idea of what you like, they will pick it out for you!  Then you will be stuck with it or will go through the hassle of returning it. 

I am in a similar position as you.  We have a small apt right now and have everything basically that we need.  So I put new kitchen electrics on my registry because mine are getting old plus some new items to make my entertaining life easier in the future.  (kitchenaid mixer, cuisinart duet blender/food processor combo)  And I also upgraded my stuff (better towels, nicer down comforter, ect)  Most of that stuff i will use when I get it and then throw away or donate the old.  I also wanted fine china so I worked it out that I will keep a few settings at my place then my mom will store the rest at her house.  (She joked that she was going to put hers away and display mine in her cabinet because she was sick of hers after 20+ years)  We will probably go to target to do some electronic stuff and few other items.  (Fiancee wants a Play Station 3, ipod docking station, ect) 

Hope that helped a little!