Thanks. That was my entry point.
Technologies like CoinJoin aren't yet implemented in standard Bitcoin clients.
Therefore, one can safely assume that all transactions signed by WeExchange's addresses are signed exclusively by WeExchange's addresses.
Given this assumption, one can get a list of most of WeExchange's addresses and transactions from only one single address.
The list isn't complete though, because transactions also have a change address which belongs to the sending wallet. The WeExchange wallet places this change address at an unusual output index, so I didn't include it in the list to avoid fan-out into other wallets.
Using the above quoted address as entry point, one will get these addresses:
http://pastebin.com/LZJPeiRM
...and these transactions:
http://pastebin.com/As66ecst
http://pastebin.com/XgsTaiaL
Now, let's sum up the total amount on all of these addresses over time:
http://postimg.org/image/wvq6x2rsl/
...zooming into early October 2013:
http://postimg.org/image/n693ky4m5/
Firstly, I was surprised seeing the first transactions as early as October 2011 - I didn't know that WeExchange existed at that time.
Secondly, I expected the biggest drop to be in mid-November 2013. However, it was early October 2013.
I filtered the list of transactions to find the big one from 3rd of October:
8a77d88fcc9ef418ec97cb2c332efd1378f21aa90188d3000a8c2e4e89f467cb
...it looks like this address received more than one big withdrawal from WeExchange:
19ENdxtYNwdsFbaEF2web7FywgQHdsNCGt
Other addresses receiving big withdrawals from WeExchange include:
115KrBsBGXvW3saUtmY6seXpXysvgd44BS
1D8zFb9jJvmdxwNmuS1TBGh1sfcqUMyRzf
That's all that I could find out for now. Further investigation would concentrate on who owns these addresses, and where did the coins go next...
Donations for my efforts go to 1PaEvsKNTDxhz4kg8rL1samkbgF65P9NMF. Thanks!