With Twitter reducing its search history to four days, it is a challenge for applications that are dependent on search results, that went not days but even months back. Several applications have taken on the challenge to fill this void and are building search indexes on top of Twitter. Topsy is one of them and it's sharing its results as an API.
When we wrote about APIs fueling an "instant" frenzy, there were only four mashups in our directory tagged instant. We've added more than that just this week, taking our total to 16 instant mashups. But the most common type of instant mashup may surprise you.