A lot of the services offer credit, which seems like a good way to go. Some of them offer a couple of months of subscription, however. New Relic in particular

A lot of the services offer credit, which seems like a good way to go. Some of them offer a couple of months of subscription, however. New Relic in particular has a little note that says you "can down / upgrade afterwards". Which sounds like you'll be signing up for a recurring billing scheme with some of these services. Can anyone confirm if this is/isn't the case? Either way, still a great deal, but be sure you keep track of all your subscriptions and remember to cancel the ones you don't want when the bundle credit expires.