PowerLogix is a well-established Mac-upgrade manufacturer. Recent innovations from the company include the BlueChip 400MHz and 500MHz G3 upgrades for older PowerBooks. The "WallStreet" PowerBook - released 1998 - ran a G3 processor at up to 292MHz. The later "Lombard" series PowerBook ran 333MHz and 400MHz G3 processors. BlueChip offers a 500MHz processor for the PowerBooks.
PowerLogix has also released its iForce 400 and 500MHz G3 upgrades for older iMacs - both of which are easy to install, according to the manufacturer.
AM Micro has announced a series of price cuts for PowerLogix upgrades, including the PowerForce G3 and G4 series and the RapidFire card, which offers USB and FireWire connectivity for older Macs.