The 707 is a classic drum machine from the end of Roland's hey day.  It was Roland's replacement for the 909.  And while it doesn't have the big analogue punch the 909 has, it still has a nice punch that cuts through a mix nicely.  Especially when compressed just right.  And, contrary to popular beliefs, it DOES NOT have the same HC, HH and Cymbal sounds that the 909 has.  They're close, but not the same.  The 707 was used on countless classic Chicago House records and tons of classic Techno records.  It's still in reletively high demand and the prices seem to be going up.  If you like the dry, jackin' sounds of early House Music as much as i do, buy one of these now before they go stratospheric in price!

BTW, the description for the 707 on this site is actually for the 505.  Slight oversight there eh?