Positive Grid BIAS Desktop
BIAS Desktop is an amazing new AAX compatible guitar/bass amp plugin that let's you basically build your own amps by selecting/adjusting wonderfully modeled components like, tubes, transformer, tone stacks and more.
There is even an AMP MATCH feature in the Pro version, which lets you capture the tone of any tube amp and have that exact tone in BIAS Desktop.
I've been using it and did a
couple review videos
about it and I absolutely love the tones I'm able to get.
Check it out
http://www.positivegrid.com/bias-desktop/