If Dad's an audiobook fan, the Kindle Touch is your best (and only) choice in the sub-$100 e-book reader range. And if he's not, it's still a great all-around touch-screen e-book reader. The $99 model is ad-supported and Wi-Fi only (no 3G).
Don't make Dad squint at the small type in his Elmore Leonard books. Get him Amazon's entry-level Kindle, and he can ramp up the size of the type at the touch of a button. (It's also the lightest and most affordable e-book reader you can buy.)
If Dad is already iPhone or iPad owner, the $99 Apple TV will be a perfect gift. It's the only streaming box that can handle Netflix and iTunes, and AirPlay lets him send content from any other iOS device wirelessly.
The Roku LT earned an Editors' Choice as the best media streamer for less than $50. It delivers Netflix, Hulu Plus, Amazon Instant, Pandora, Crackle, and literally hundreds of other online video and audio channels. If Dad can live without iTunes and YouTube, this one is a no-brainer.
Don't get stuck handling tech support for Dad. With the Nook
Simple Touch, the staff of his local Barnes & Noble store is available to answer his questions instead -- a win/win for you and him. (Spend $40 extra, and you can upgrade to the new version with a built-in GlowLight.)
Don't fret that the Klipsch Image S4s are a few years old -- they're still one of the best deals out there, and a perfect gift for Dad. The S4i, which can also be had for less than $100, integrates an inline remote and built-in microphone for iPhone calls. For Android smartphone users, Klipsch also makes the S4a.
There are a glut of Bluetooth speakers with rechargeable batteries out there, but the $99 Soundfreaq Sound Kick strikes a strong balance between size, sound quality, and price. If Dad is savvy enough to stream music from his iPad, iPod Touch, or smartphone, this is a great gift.
Logitech's Harmony 650 may not have the fancier screen of higher-end models, but it's a very solid--and very affordable--universal remote that can replace up to five of the clickers on Dad's coffee table.