Definitely a mempool.bin issue.  Armory attempted to broadcast it, but Bitcoin-Qt was probably disconnected from the network when it tried, and now it's stuck (for reasons that are difficult to describe).

Close Armory
Close Bitcoin-Qt
Remove ~/Library/Application Support/Armory/mempool.bin.
Restart Bitcoin-Qt
Restart Armory
Send transaction again

If this was an offline transaction, you don't even need to recreate&sign.  Just select the file in the offline-broadcast window by "Show All Files" at the bottom-right of the file-select screen.  Select the *.SENT.tx (normally you select a *.unsigned.tx or *.signed.tx). 

If you are using an older version of Armory on the offline computer, there may be other issues, but those will be resolved with the new version of Armory posted on the RAM-Reduction testing version thread.

Yay picobit!

https://dl.dropboxusercontent.com/u/1139081/ArmoryTestingReleases/Armory.app.0.89.99.9-testing.tar.gz

That 40 MB tar.gz unpacks into a 136 MB Armory.app directory, which should be double-clickable to run Armory.  I successfully compiled it on my MacMini, after review the build-app.py script that picobit gave me, and then successfully running it.  There was a few hiccups in the build process, but it ultimately worked.  And kudos to picobit for not only giving me a script, but being diligent about creating and sorting log files for each command so I could easily figure out what went wrong.  

Please test it on your OSX system.  Especially on 10.9, and especially on any systems where the download from the webpage didn't work.  I want to find out if this .app works better than the one we originally got from higuys.  I'm hopeful based on els' statements that it worked on both 10.8 and 10.9, but I definitely need more empirical evidence.  

By the way, this is actually 0.89.99.9.  This has a feature merged in from CircusPeanut that fixes the broadcast issue people experience when using older versions of Armory on the offline computer.  The issue was that the core devs implemented a soft-rule requiring normalized signature padding, and older versions of Armory didn't do that.  Thus when you sign with the older version, the tx will be rejected if you are running Bitcoin-Qt/bitcoin 0.8.2 or newer.  This version works around that by exploiting the same transaction malleability that the core devs were trying to reduce!  It adjusts the signature padding of the already-signed transaction -- it changes the hash of the transaction but makes the transaction not only valid, but isStandard() so it will broadcast correctly.  

If you are experiencing that broadcast issue, you can:  (Linux) Pull the latest testing branch and use that (OSX) Use this .app (Windows) Wait for the next testing release.  

Depending on your country, you can go to a bank and make a cash deposit to do a wire transfer.
You should read something about that in your country.

welcome