TextMate is all that and a bag of chips, like any powerful tool,  
there is some learning curve to take full advantage of.  Use it for  
everything and explore a lot and i expect you'll be very pleased.    
If that doesn't work for you, you could check out http:// 
www.radrails.org/ .  Personally i can't speak to its quality as the  
only thing that disappoints me about TextMate is that i've only just  
begun to utilize its potential.  You can learn a lot about TextMate  
from Allan's (and others) screen casts.

p.s. Looking forward to the book James!