Pub Med.
Skyscape platform. OCM is free and not bad. See if Navy or your hospital library has a subscription with which you can get DynaMed for free.
Both AF and Army provide free subscritpions to Lexi Comp mobile. Can't imagine that Navy doesn't. This about obviates the need for other drug databases, none of which is as thourough. Lexi also has other useful databases such as lab-tests and ID databases.
Mediquations is the only medical calculator that I bought that approaches the quality of the iOS "medcalc" (which at $0.99 is still the best medical calculator on any market). Still not as good as medcalc, but suffices. I despise QxCalc, but others will probably throw it out there as a freebie.
CS ACLS is one of the best code apps IMO. It's inexpensive and has the full 2010 PALS guidelines as well as ACLS (just have to remember to set preferences to AHA over European guidelines) but also functions as a code-dose calculator. Other OK code dose calculators are SafeDose (which has other decent content), PediStat (which is greatley overpriced for Android. I had it on my iPod Touch) and PediSafe (never used it. Decent reviews). The thing that makes CS ACLS better than these in my eyes is the inclusion of the actual PALS guideline which the others lack.
Still love Eponyms. Still free.
Pediatrpedia is decent for a growth parameter and BP calculator and is cheap.
I have owned a Harrient on Skyscape in the past and now one in the Unbound Medicine format. I like neither and think neither are worth the money they cost. Both with poor navigation, though content is good.
Things I've looked at but have not chosen to purchase: 10secondEM and PalmEM.
I've had Medscpe and think the clinical content is decent, but find the navigation somewhat clunky so haven't resinstalled it of late. I don't need the drug database, so it's not worth the space right now.