Before we go any further, I have to give credit where credit is due. We would not have half (1/4, maybe even) of the fun, educational apps we enjoy, if it weren't for the Smart Apps For Kids blog.
Reviews by a dad, who tests out the apps (when age-appropriate) with his own children (and evaluates apps for older kids himself). Bonus: one of his children has an autism spectrum diagnosis, so there are personal-perspective reviews of special needs apps and notes when particular apps cover skills commonly addressed in therapy.
Subscribing to their Facebook page gets you their daily "Good Free App of the Day" (GFAOTD) posts. Some of these are always free, others are free for a limited time. App developers have clued into this site and will often intro new apps or big upgrades by making them free here to get the word out. We've gotten quite a few free apps this way.
Perhaps my favorite part of Smart Apps blog, though, is the option to sort their reviews by age-level. I use this almost exclusively to find apps for MS (almost 14 [ack!]), a hard age to find fun, educational apps for (not that they're not out there, just that not everyone and their [his/her] dog are talking/blogging about them). Be sure to check out their 12+ section.
One other section not to miss is their "Best" pull-down menu, which sorts reviews by 5-star, top picks, editor's top 10, reader's top 10, etc.
So, now you know. I don't, actually, spend all day researching educational apps for my kids. It's the cold, hard truth.