As the question notes, Poker Chips in place of money is quite viable. I don't remove the money, just leave it bagged in the box.
Gaming stones or poker chips can be used to track victory points as well.
On some sports games, counters or standups are replaced with meeples or minis readily. I've found that meeples fit beautifully on the Crash Tackle board, for example.
Any game using a pawn or meeple can usually be replaced with nice minis.
Any game using cardboard stand-ups is readily able to use minis in place of the stand-ups.
The issue of condensing depends a lot on how you play.
Putting all one's Ticket To Ride games in one box simply means not being able to sell them off separately; the component overlap is quite high.
Putting all one's 18xx games in one box, however, may result in a jumbled mess.
Putting all one's Dominion cards in one box is rapidly approaching impossible, but since the core boxes are equipped with decent organizer trays... it really isn't a superior approach, aside from issues of volume.
Many card-only games can be readily condensed down to just a zipper-bagged set of cards and the rules.
The typical condensation level apparently is a game and its own expansions.
My Carcassonne box can't hold anything more, but has in it: Carc., River I & II, Inns & Cathedrals, Traders and Builders, Tower, Count, Princess & Dragon, King, and one other small one. The Tower literally is filled with all the tiles.