I recently discovered the joys of ExcelDNA, which lets you do spreadsheet extensions using C#. One of the first things I did was spin up a plugin that allows users to request data elements from CSV files hosted on a server, essentially a giant remote VLOOKUP. The product uses TCP/IP so it can run anywhere - client self-hosted, or remote over the internet. Throughput was pretty high - 70k elements per second over a network. This, and I'm a novice programmer.

So I look at Blockspring, and my first thought is that I don't quite get it, although if they ran on proprietary, internal data sources, it would make sense. (Do people really download Amazon listings into Excel? I suppose). Or, if they could get a company like Factset or Bloomberg to let them do direct data pulls from their databases, then you'd get masses of high quality data to analyze.

In terms of the core "into excel" functionality - maybe I am understating my novice capabilities, but ever since I discovered ExcelDNA it seems like you can do almost anything with Excel and C#.