I am fairly new to TL and am surprised that no one has mentioned the eSignal QuoteTrader package with reference to the DOM. This has also been integrated into eSignal itself and they apparently have over 1000 people using it. It connects to MBT, FXCM, IB and other brokers I believe. I have it working on MBT and this dom has a volume profile like chart that builds up intra day. Setting up can be tricky and time consuming but it is a useful way of additing the DOM to FX trading. As far as I am concerned this is the way this stuff HAS to go. Also spoke to JDFX recently, who have an ok platform (excellent fills though) and they say they are planning to add the DOM (the sooner the better).
I have not checked out the Ninja interface yet and must do so shortly, but I do like the eSignal one that I am using with MBT Navigator at the moment.MBT are great except their commissions do eat into profits, whereas providers like Currenex, JDFX, and Hotspot are a fraction of the price, though you need a much larger account to open up their. MBT offer choice fills on a $400 account, so one must not complain too loudly!
I think the reason the DOM has not been added to most FX broker platforms is that many FX brokers take the other side of the trade against the client (who in most cases loses his/her account eventually) and therefore the DOM may be slow to arrive on the desks of the FX trader as it gives the trader a much easier shot at order entry and profitability (imo!):crap:
However with Hotspot and other bigger players adding the DOM perhaps the other slouches will catch up and give some value to us poor FX traders!