I agree, we need more coin-for-coin exchanges. I started working on an exchange once upon a time but had too many problems with Dwolla and C# not playing nicely... Perhaps I could modify what I've already got to serve as a BTC/NMC/IXC/GRP/DVC/MBC/etc exchange...

As for current value... While I see no reason to tie USD values to difficulty, I think difficulty could be a great tool for estimating the worth of coin-to-coin exchanges... IXC diff is currently 4, BTC diff is currently 1888786.70535 so it seems to me that 1 IXC should be valued somewhere in the neighborhood of 4/1888786.70535=0.00000212 BTC (rounded to the nearest satoshi). Do the math the other way to find that 1 BTC ~= 472,196.67633750 IXC.

Of course difficulty 4 won't last for long, even with a measly 2 GH/s for the whole pool, so it may be too early to attempt such a valuation.

Of course, we have namecoin to base our math on too... Already-existing resources have shown that historically NMC is valued at about 2/3 (67.9%) of what this ratio says it should be (on average). The argument that namecoins have intrinsic value because of the service offered by the network might be slightly true, but the bitparking exchange has a volume much higher than the actual NMC spent on registrations, so they're likely being traded by speculators much the same as BTC. If we apply this fractional value to IXC we get the following:

1 BTC ~= 320,621.54323316 IXC
1 IXC ~= 0.00000144 BTC

Yeah let's redo the math after a few weeks worth of difficulty updates