Hmmm… not sure. It depends on who you ask. In many cultures cash gifts are acceptable and expected. They go as far as pinning money on the brides dress, handing the groom wads of cash during the receiving line, or having money dances. For others, it may be viewed as rude to request cash so tread softly… 
Many couples today tell us that they really do not want to do a gift registry and the most common answer when I ask why – “We already have everything” When I ask is there anything you really need, a common answer is – “MONEY!!!” Most of them are planning to purchase a home, go on a much needed honeymoon-vacation, remodel an existing home, or pay off some of their “wedding” debt.
So how do you ask your guests for cash gifts in lieu of toasters, blenders, pots/pans, dinnerware, silverware, photo frames, etc. Try writing a poem and explain to your guest WHY you are requesting the cash. You can post the selection on your wedding website or simply explain it to them when they ask where you registered but DO NOT include it in the invitation.
While searching the worldwide web, I found the following:
We’re dreaming of a honeymoon
and we hope our dreams come true…
if you helped us fund our trip
we’d be so grateful to you!
We have two of EVERYTHING because
joining lives means joining households, too!
So please don’t give us another toaster –
a gift of money is what we’d appreciate from you!
We didn’t register
We don’t need more stuff
But when it comes to financial help
You can never have enough!
We have our hearts set on a trip to Hawaii,
We’re saving every nickel and dime.
So if you aren’t sure what to get for a wedding present
A gift of cash would be just divine!
