There's an app for that.
Pardon the cliche. Couldn't resist. I have Comic Reader Mobi ($14.99) installed on my iPhone. The app itself is pretty good, but the iPhone/iPod Touch's small screen just doesn't lend itself well to comics. Having to constantly zoom in on the text bubbles is pretty distracting and detracts greatly from the comic reading experience. Sure, you can read comics on it, but I didn't find it all that enjoyable.
So far, I've found the Fujitsu P1620 tablet to be the best when it comes to reading comics (8.9", 1280x800). It's just a wee bit heavy, though and I'm afraid I'll break it (mine has a hard drive instead of SSD and it's constantly complaining about being jolted around even at the slightest movement). I got myself a Viliv X70EX (7", 1024x600) and it works pretty nicely. It's not as nice as the Fujitsu but at least it's not constantly complaining about me bumping it around.
If you're buying the iPod Touch mainly for comic reading purposes, then I suggest you look at other options. If not, then it's a pretty useful multi-purpose device. I must say it makes for a nice compact ebook reader.