No matter how bad an idea it seems before you have children, at some stage one or more of them will decide that he or she wishes to try and collect a whole set of trading cards. The only ones that our offspring have been that interested in are the Doctor Who "Battles In Time" ones.
As we have now completed the third "new" Doctor Who series, the size of the deck of cards has correspondingly grown, and it now numbers 675 in three series.
Unless a series of trading cards are incredibly popular, there are unlikely to be enough people seriously collecting them in the circle of a child's friends to make it feasible to complete a collection. So, I thought to myself, why not write an internet based thing that would allow trading with a wider circle of people?
I made some progress, with PHP and MySQL - I was able to select multiple decks, write details of individual cards, set up cards available to trade and wish lists, scan other peoples' lists to look for possible exchanges. But, as with the Open Solutions thing I came up with, one of the real problems would be making the site known. Additionally making it look good and testing it was really more than I thought I was able to achieve.
There are other swapping sites around - like this one. But although this has a section for trading cards, it isn't really designed for that sort of transaction. I knew what I was looking for, conceptually, and was interested to find something very close to it the other day - here. It's not beautiful - but it does seem to offer a good system for getting in touch with people who want to trade the same thing as you. Now to see whether we can get closer to completing the collection!