The best 500 I've personally seen was owned by a friend of mine... It was approx -
A500 w/ VXL 68030@28mhz + 8MB FAST on card.
DKB MegaChip 2MB Agnus
ECS Denise
DataFlyer/DataRam 105MB HD/4MB RAM
1.5 MB Baseboard Supra (for the MegaChip?)
This system was back in 1992, or so, so it was pretty cutting edge for the time.
(...until I bought my A1200 with the GVP '030@40mhz and 0wn3d him. hehe!)
I have a unique add-on in my closet that would be a prime find for any Amiga 500 expansion fan. The Bodega Bay Zorro II expansion box. It'll turn an A500 into an awkward looking A2000. It's large, heavy, and guaranteed to not fit on any conventional desk you've ever seen! Picked it up at an old C= auction for $10(!!) Guess no one wanted to lug it back home with them... I wonder why.... :-P