Spam, you could just turn it to flight mode i suppose? Anyway, still valid question for the ipod touch also.
To answer the original question, aeroweather is very good for TAFs & METARs, whilst iPorts adds runway length and orientation data. Pilotwiz is aimed more at the GA market but does have some handy conversions and also a very easy to use hours calculator. LogTen is an excellent logbook app, but it costs to get it in any useful format other than the free (very limited) demo.
Not strictly aviation but Tymelynz is great for tracking your training requirements, and medicals, CCS etc, whilst XpenseTrkr is invaluable for keeping on top of your JPA claims for trips.
MarinerSoftCalc allows use of MS Excel documents, but at the moment is a bit buggy, despite its £5.99 price tag. Most spreadsheets I have tried to use didnöt fully work, but they assured me by email that they are working on the bugs.
Thats about it from me, except iPint for those dry dets of course!