This is a great thread, and I love the pics Impact619!
I have 132,000 miles on my 2005 Xterra, and just spent about $2K replacing the cat converters and a "general" tune up.
Right after I bought it in December of 2009 the coolant mixed with the trans and I had to spend about $700 to replace the cooling system (better than the $5,700 Mossy Nissan quoted for the trans/cooling replacement), and then about 6 months after that I spent another $900 replacing the ECU unit and replacing the Mass Air Flow sensor!
I still love this Xterra, and look forward to the next 80,000 miles!