Not too long ago I decided that my Emperor's Children could use a contingent of Slaanesh Daemons to back them up. Luckily, I managed to get hold of some of the old metal Daemonettes on eBay for a reasonable price (about £20 for 10). For those who don't know, they sometimes go for several times that sum and I'm sure that right now there will be a "buy it now" listing for 10 asking a good £100.
I actually quite like the plastic ones too, but I have used them a lot in the past and in various conversions, so I wanted some different ones just to differentiate them aesthetically. On the table-top I was thinking I might take Daemonology and try to summon them as it could be a good laugh. Either that or I might do a small allied detachment added on to the main force. Only time will tell with that one, but I'm sure it'll be fun.
I really wish that Games Workshop would make a chaos supplement people actually want to see. People play chaos in 2 ways - a mixed Black Legion type list with all the gods represented, or as fluff armies that only have units of one of the gods (e.g. Nurgle only, or Slaanesh only). Why they haven't made a supplement for these types I don't know. They did do Khorne Daemonkin, but then never made any for the other gods. I quite like the idea of a proper Thousand Sons/Tzeentch force, but at the moment it isn't happening. Obviously I'd like to see a proper Slaanesh codex the most. I'm not asking for it to be super-competitive, but a few bonuses and formations that rewarded you for taking a themed force would be nice.
Now I just have to go and paint the other 4... what "6" is the official number for Slaanesh, what do you mean it isn't a legally field-able unit!