Category setup

I have the classified theme and would like to setup categories. They are there, but it’s ugly as hell. Why? Because it’s a long list of subs. Is there any way to do where the main and sub categories are drop-down according to subject.
Say if I have tropical fish as main and a slew of subs under it. The way it’s setup right now the main might be an icon or might be text which is alright except the icon sizes are screwed up, because they are either too big or the -small size only sows a sliver of the icon which is useless.
The subs however is a long list of text going downwards.
If I have dogs as main the subs will be under it in a long list of line after line until it reaches the last one as there must be 3000 fish species and 2000 dog species.
Also in category I should be able to do parent/main sub category as a hierarchical. Say I have fish as main, shark as sub and shark types as sub. Capish?? In dogs I should have Dogs as Main/parent, terrier as sub and a bunch of terriers as subs. Capish?? All this right now looks very very ugly.
Have you guys ever looked at what the category setup offers??
Display max number of main/parent categories and display max number of subs and display selected categories. Do you think these looks like stupid or usable?? I know Mark is english and their use of words and their meaning not quite right on spot many a times, but comon,,,, why would I want to do say 20 categories and 200 subs and then limit it to ??? 10?? or just display some?? Who designed this into it?? Shouldn’t it say main/parent, sub, sub, sub? and then take out the ones I don’t want when time comes. Why make them then not display them?
I have no idea about coding which I am sure would do what I think would be nice and also logical, but the theme should offer this basic function since it’s a classified theme that usually have a myriad of sub categories. Look at craigs list, ebay, amazon just to name the biggest ones. Look at pets4homes, look at…. I could list a million sites. Imagine all ebay listing would be one long line of subs. Would that make sense?
So my question is how to do a drop-down category for main and then sub and sub and sub and sub and sub and sub and sub……. and sub categories?? Or am I missing something on the category setup??
Thanx very much