Has anyone dealt with:
http://www.thewheelsmith.net/
(I found them through an ad in Street Rodder magazine while waiting to pick up my brother-in-law at the airport.)

What does 5x114.3 equal to in inches?
Does 5x4.5 fit correctly?

I called and left a message with them earlier.  I plan to ask about offset.
As several seem interested in wheels of this type, I'll report back what I am told.

Well . . .
they would physically fit the lugs, but would have offset and brake clearance issues, as they are designed for rear-wheel drive (and drums brake) cars.  They made some for PT Cruisers and HHRs, but have had serious vibration issues he said were inherent in alteration of that wheel design for a higher offset, front wheel drive vehicle, esp. one with disc brakes.

So, no dice on those.
Anyone know of somewhere else that might work?

So far, it looks like the "Spider" caps might be the only "hot rod" option.

Yeah bob did the conversion for you but I have already figured out, by trying to use jeep rims on my scion(not gonna happen), that 5x114.3 is exactly the same as 5x4.5. 

Also I saw a PT with some cool looking caps today that gave it a retro look. I will see if I can find them.

Now there's a thought, eviljack... 4 yellow donuts

Yep.
Center caps require flanged made into the inner ridge of the rim.  The STOCK Scion one doesn't have one.  So, I was looking for Steelies that did.  Unfortunately, the ones made are for near zero offset Hot Rods and won't work on our xBs. IF I could find a steelie with flanges that would fit, one could use center caps.

That would be:
5X114.3 TRUCKS
Dodge
Dakota 2WD (1991-1993)    
Ford
Bronco 11 (1982-1983)    
Grand
Cherokee (1993-1998)    
Mazda
B-Series (1996-2003)    Navajo (1991-1994)
Mercury
Grand Marquis Wagon (1988-1991)    Sable (1988-2003)
Toyota
Pickup 2WD (1969-1994)    Tacoma 2WD (1995-2003)

5X114.3 Cars
Acura
Integra Type R (1997-2001)    RSX (2002+)
CL (1998-2000)    Legend (1991-1995)
TL 3.2 (1996+)    
Chrysler
Caravan (1999-2003)    LHS (1995-2003)
Chrysler Sebring (1995-2003)    
Dodge
Stealth RS Turbo (1994-1996)    Stratus (2002-2003)
Talon(1990-1998)    Avenger (1995-2003)
Ford    
Ford Probe(1989-1997) Hub bore 59.6    
Honda    
Prelude (1997-2001)    Honda CRV (1997-2003)
Civic Si Hatchback (2002+)    
Infinity
Infinity I35 (2000-2003)    Infinity I30 (1996-1998)
Infinity G35 (2004+)    
Lexus
ES300 (1997-2003)    GS300 (1993-2003)
GS400 (1998-2002)    GS430 (1998-2003)
LS400 (1990-1994)    IS300 (2000+)
Mazda
929 (1988-1994)    626 (1988+)
Protégé (2002+)    Protégé 5 (2002+)
Mazda3 (2003+)    MP3 (2002+)
Mazda6 (2003+)    Mazda5 (2005+)
MX-6 (1988-1992)    RX-7 GXL GTU Turbo II (1986-1992)
Mazda RX-7 (1993-1996)    
Mitsubishi
Diamante (1991-1996)    Eclipse (1989+)
Galant (1997+)    3000GT SL (1991-2000)
Lancer Evolution (2004+)    
Nissan
Altima (2002+)    Maxima (1989-2003)
240SX SE (1995-1997)    350Z (2004+)
Toyota
MR-2 (1990-1995)    Supra (1986-1996) including Turbo
Camry Solara (1999-2003)    Camry (1992+)

I'm not sure any of those came with 16 inch or higher steel rims that had center caps, rather than full cover caps.

Yet, good to know what matches, in case someone like another make/model's stock rims!
(That list would make a good sticky post in the rims section . . . hint, hint)