This site is part of the Forces-Reunited site and whilst searching the index is free you have to pay for viewing the records themselves. They say they have 1 million+ records dating back to before 1630. Some of the more recent information has been submitted by members of the Forces-Reunited site, but this is all a bit unclear. Worth a look even if you don’t decide to subscribe.
http://military-genealogy.forcesreunited.org.uk/
Technorati Tags: Military Genealogy,Forces Reunited,genealogy

I believe they have over 2 million records now, so a pretty good database really, albeit that no database will ever cover everything as there have been many many millions of service people since 1630 and thats for sure!
I’ve used it: a darn sight fairer than most as it doesn’t use ‘credits’ you get unlimited use for a month from £6.29 which is pretty good (£4.99 + charges and vat)