Dragonplus issue #38 mentioned using MTG cards to help with your gaming. Issue 38 MTG article

Here are some additional ideas I have.
Old cards are easily found in bulk so collecting enough is relatively cheap. Careful though... it can be addictive.. 
Get 1,000 basic lands and 1,000 non lands to start.  Also, specific cards are easily had, just cost more.  
These can be found on eBay or at your local store where I would check first.  If you have some laying around, great!
Pretty much ignore the game text but focus on the title, artwork, and the flavor text instead.  
The Wishcoin crab is my favorite.  It makes the crab something fun and interesting even though its really just a crab.

Duplicate cards and tokens are no issue and in most cases, desired.  
Any excess cards can be used to create tokens/pogs for the table.  Saw a guy do this on youtube.  Simple and easy.

First thing that comes to mind are Search Decks.  Players will flip cards in these decks to "search" an area. (good for solo also)
A search deck will be mostly basic lands.  
Add non basic lands which are quest or encounter locations that fit the theme.  Tranquil Bay or Quarry for example.
Add monsters/creatures that can be found in the area.  These are your wandering monsters.
Add special monsters/creatures that are quest targets.
Add in other cards that could be events or impediments to the party. 
Cards like Undegrowth, Wall of Vines, various Fog type cards, and Duress fit here.  Call the Cavalry might be a card the party can hold and use at the right time.

The players now start flipping cards to search for the quest targets.  
The cards flipped represent time so after so many cards, day breaks or night falls, that sort of thing.  

Cards can be segregated to NPCs, monsters, events, and traps/impediments. 
New monsters can be created using the attack/defense numbers of the card.
Using the DMG guide, Level 1 creatures using the 1/8 CR line and then work up from there.
If a creature like a spider is a 1/4, use the appropriate line for the attack factors and a different line for HPs and defensive characteristics.
The spider then will have a small attack factor but will be hard to hit and have more hps.  Something different to keep them guessing.
A Netcaster spider can be modeled by giving it a ranged attack that acts like a web spell if it hits the PC.  

A deck for tracking time in dungeons acts is a search deck.  
Each card represents a set amount of time expended and contains wandering monsters, mobile quest targets, and traps/events.
So if the party searches every room, have them pull a card each time. This way they realize that the more time they spend in the dungeon, the more dangerous it could be.    

Somewhat interesting but wouldn't 2000! cards be pricey?

Not as bad as you would think.  eBay has a 1,000 cards (non basic lands) for $20+tax delivered, Amazon has some 1,000 card lots for $16.

Basic lands are about the same although a bit more it seems which surprised me.  I bet the local store would be glad to sell you some.

I may have exaggerated on the card count.  You could be inspired with fewer cards for sure. :-)

I found a 1,000 ct basic land box for $31, if you don't mind them being in "not English" you can get 1,000 for $24. 

A 400ct of basic lands can be bought new (Land Station) for $23.