I teach my boys that they invite their friends to spend some special time with them, and that not everyone will (or can afford to) bring a present.
Ok, pretty much everyone does bring one - but in the general rush will they even notice?
At my ds1's 8th (small party at home, 7 guests) two of them didn't bring presents - I certainly didn't notice at the time and only know it was the case because one parent brought a present when he came to pick up at the end and the other brought one into school a couple of days later.
DS1 didn't notice either.
And that is a relatively small party where he opened the presents as the guests arrived.
(I accept that ds1 was 8 and it might be more problematic with smaller children).
At ds2's 5th one present was a dvd, when we were looking at the cards after there was also a fiver in the card - honestly I was 
, the dvd was more than enough (it may have only cost a couple of quid, I have no idea, but it is the thought that counts).
Another of ds1's friends always gives a box of chocolates (celebrations or similar) and usually recycles a card. DS1 LOVES getting chocolates, as it is such a rare thing as a present for children, and quite honestly barely looks at the cards so I doubt he even notices.
So, I think any of the options on the thread are fine - though I do like the blaming the useless DH one 
.