Some suggestions
 

Okay, some of these have been mentioned before, but just for the sake of completeness I'll repeat them anyhow. Features I long for:

- Abillity to stop a search without having to close the search window.

- Multiple selection in download window

- Abillity to control wether I prefer to get one file from many hosts or many files from many hosts. Let me elaborate on this: sometimes I download several big files. And even though a file may have hundreds and hundreds of available servers, Xolox will often rather download many files at once instead speeding up the one file I want. To keep with the "easy to use" paradigm, Xolox might ask this the user at first startup or let it set with a slider.

- Same for uploads. I really loathe to see 4 guys downloading from me and each only getting 2 kb/sec, whereas I would prefer it, if only 2 could download and each would get 4 kb/sec.

- Warning if you already have a file in one of your directories.

That's all I can think of now ... maybe more later.