My Blazer has 175,000 miles and it runs great. I am just trying to get a idea of some stuff that I should replace or clean that the ordinary vehicle owner wouldn't do.

Things I have Already Fixed Or Replaced:
1. Transmission Mount
2. EGR Valve
3. Full Tune-Up *About 200 Miles Ago*
4. Flushed Out The Radiator

What are some other things that would be good to do?

i'd make sure you keep the front end greased up. the person who owned my car before me was a lazy schmuck and i needed all 4 balls joints when i bought the car due to lack of grease.

http://www.automotiveforums.com/vbulletin/showthread.php?t=379175

You can clean the IAC valve, too.

Run a bottle of techron through occassionally to keep the poppit valves clean.