there is also:

ow: indicates when someone feels pain

woop: indicating when someone is cheering.

 Bah: Indicates derisive dismissal.

This is also a very naughty word in Sheep-ese

This is also a very naughty word in Sheep-ese

 very funny, Sheep

Aha - isn't that also a popgroup from Norway

D'oh! - requires no explanation...

Bleh! One of my favs when anything and everything is just plain crappy.

Does ffff need explanation?

phwoar!!

*exclamation when a hottie is spotted *

grrr - anger

ugh - disgust

Eep! - when someone has been poked unexpectedly

phew - when danger has passed

edit:  Whoa! - normally following a DRASTIC breach of personal boundaries

Meh

I personally like "gwarg" because it's so versatile. It could be an alien or an evil witch dying, somebody doing something completely disgusting or the incomprehensible beeping of a robot menace.

Japanese has tons and tons of onomatopeia and it's a lot of fun to include it in writing. For a little breath of fresh air, here's some examples:

Teku teku - One of my favorites because it's so specific, it is supposed to represent the likeness of walking, but not just ordinary, walking in contrast to not using a vehicle, in other words it's there to show the fortitude and perservance when you decide to get there by your own two feet.

Odo odo - This is an expression for when you can't calm down because you're afraid or anxious about something.

Kasa kasa - This is the sound of two dried out things scraping or moving against each others, like dried leaves or a dry hand brushing against denim.

Gabatto - The motion of somebody getting up quickly or suddenly diving down and other such similar motions.

Shittori - The feel of something soft and velvety, calm and quiet, like deliciously smooth chocolate cake or rich shampoo.

Gito gito - The disgusting, sticky, gooey feel of grease and oil.

Nghhhh - my personal favourite, expressing that sort of pleasure/pain boundary you only get with realy good sex...

gah -  frustration or excitement

tsk tsk  - disaproval

Shittori - The feel of something soft and velvety, calm and quiet, like deliciously smooth chocolate cake or rich shampoo.

Perhaps best not to share how I'm reading this ...

So these words do have meaning after all lol

zap, wop, wallop: these take me back to my comic book days

eh- only if your Canadian lol

huh- disbelief or questioning

these and the two I previously posted are some of my favourites