An Elbox tower and Mediator will utterly transform your Amiga.
The tower is a well made and sturdy piece of kit, with plenty of room for whatever you wish to put in it. The Mediator is quite simply THE most significant Amiga add on since the advent of PPC. You have access to a large number of very cheap and high performance PCI devices which outperform and are considerably cheaper then the Zorro equivalent.
There is a downside though. If you want USB or Soundblaster then you have to buy Elbox's own drivers (£50 and £20) respectively.
There was talk of a PCI mounted PPC accelerator card some time back, but Elbox haven't released any new details in over a year. The cynic in me says that idea bit the dust, but I'd love to be proved wrong.