For $5 per month, here's what I've already used:
2 feats from the gladiator articles
4-6 encounters I plucked from Dungeon articles
Fluff from the gladiator articles
The encounter builder to estimate how many monsters of what type to use when building encounters
The monster builder to stat out (approx) new monsters in my campaign
The compendium, to cut and paste monsters, powers, etc in putting together all encounter info on 1-2 pages.
Here is what I'll use for sure from teh first paid month, but haven't:
more stuff from teh gladiator articles
the domain of dread article - great stuff
1 adventure as written (pretty much) for a different campaign
that's what I got for my $5 in the first month. It must have saved me 10-20 hours of prep time, maybe more.
That doesn't count the barbarian and bard previews - both of which will be used by my kids extensively, nor does it count the character builder beta....coming next week.