[Acer Iconia Tab A100] racer25x:
EBOOKS:

I use mine a LOT for eBooks (especially technical manuals from O'Reilly). I'm also slowly "acquiring" all of my old magazines as .pdf files so that I can re-read them whenever I want to :-) Here are some of the apps that I use for reading. ezPDF is the best (stand alone) .pdf reader. Aldiko is the best epub reader, and there are tons of free books available through the Kindle app. Overdrive is the app that you have to use to borrow ebooks from most libraries. It's pretty awesome to always have hundreds of books and magazines with me while carrying something not much larger than a singe paperback.

ezPDF Reader:

market.android.com/details?id=udk.android.reader

Aldiko:

market.android.com/details?id=com.aldiko.android

Kindle:

market.android.com/details?id=com.aldiko.android&feature=search_result

Google Books

market.android.com/details?id=com.google.android.apps.books

Overdrive Media Console:

market.android.com/details?id=com.overdrive.mobile.android.mediaconsole

Comics are also pretty awesome on the tablet. Android Comic Viewer allows you to read comics in both of the formats you can "find" on the internet: .cbr and .cbz. Marvel also has a decent enough app for their Digital comics.

ACV:

market.android.com/details?id=net.androidcomics.acv

Marvel COmics:

market.android.com/details?id=com.marvel.comics

XKCD Viewer:

market.android.com/details?id=net.bytten.xkcdviewer

VIDEO:

Movies and (sort of) TV on my tablet are awesome. I like to fire up Hulu or Netflix while I'm in the kitchen or while I'm doing stuff around the house. With my tablet, I can move the "screen" around with me as I go. I also recently gave Amazon a bunch of my $$ for Prime, so I'll probably load the Amazon VOD app soon. I have a lot of my DVD's ripped as MP4's, so it's pretty easy to load movies on to the SD card and have them for offline viewing. The only down side there is that if I use a slow card, sometimes the video and audio will stop being in sync after about half way through a movie.

For Hulu, I use Flash Video Browser to watch (free) Hulu, instead of either paying for Hulu+ or modifying the Hulu apk to allow me to watch unrestricted. It's a paid app, but I got enough use out of it the first day to warrant the 99 cent purchase price.

Flash Video Browser

market.android.com/details?id=com.danielhlockard.flashbrowser

Using the HDMI out to a TV when I'm at a friend's house and don't want everyone to have to crowd around the tablet it pretty nice too.

AUDIO:

I haven't used it for audio books (yet), but it's pretty snazzy for streaming my library back to me from either Google Music or the Amazon Cloud Player.

GAMES:

I have a tone of them for free through the Amazon App Store. I also have a couple that are more optimized for the dual core CPU that I got through indie bundles, etc. I mostly stick to like 3-4 games at a time and slowly rotate through them. My buddy swears by the minecraft app . . allows him to play on his tablet while still "spending time" with his GF when she watches TV shows that don't appeal to him.

My web surfing on it tends to be spawned from using Facebook, twitter, Google+, etc. and finding cool links to check out. Although I may have taken my tablet with me when I was out for the day, and then tethered to my phone so that I could get on and check eBay bids from time to time ;-)

The Chrome to Phone app is pretty handy for web surfing as well. It allows you to send links from your browser to your android device(s) and be able to pickup reading on the phone/tablet.

No discussion would be complete without an obligatory mention of some of the other apps I keep installed:

Sketchbook

Evernote

Google Docs

Dropbox

Box.net

Youtube

MX Video Player

Twitter client of your choice

Tunein Radio

Wifi Radar

Wifi Analyzer

If you're going to use apps where you planning on doing a lot of typing (Evernote), you might want to invest in an alternate keyboard.

And, keeping in line with the rest of the humorous comments, I should probably also make the obligatory "adult material" comment. LOL