OK, so here's a wish list for Brickset....
All of these suggestions are I believe aligned with the site ethos, namely to be a hub for collectors.
1. An extra field when we browse our own collection where we can capture the condition of our sets - sealed/boxed/loose at a minimum. Better still would be a further field to capture complete/incomplete for the unsealed sets, but this is less critical I think. A complication is for those with multiple copies of particular sets, some of which are sealed, some of which are loose etc. - it'd make the browsing list quite long and unwieldy. Perhaps therefore there could be an option to switch off displaying condition etc. for those that aren't interested.
2. When we view the collections of other members, it'd be nice if the list would cross reference with our own collections so that those sets that we also own are highlighted. Nice to compare who has what.
3. When we view other peoples' collections, it'd be useful to see how many multiples they have, and the condition of the sets per suggestion 1 above. Two reasons for this - one is curiosity. The other is to increase the potential for trading on the forums. How it would work is when you register you select whether you're interested in trading or not. Then, if I'm looking at the collection of another member who's interested in trading and see they have multiples of a set I want, I could contact them via the forums and ask if they'd be interested in trading or selling. I realise this could be quite intrusive and potentially controversial, but the option to opt in or out of this partially addresses the concerns, and I thought I'd suggest it to gauge the reaction....