People ask Hyperreal to promote their parties for them all the time, or they want to know where to find info about upcoming parties in their area. There are several services here that you can take advantage of if you are one of those people.
Since there are so many ravers spread out over vast geographic areas, there exist rave-related web sites, mailing lists and calendars that are devoted to specific cities, states, and other regions. Hyperreal hosts some of these regional mailing lists and web sites. Posting about a party to a mailing list for your region is one of the most effective ways to promote online.
Now, before you get any lame ideas about spreading the news about your party as far and wide as possible by posting to every list you can find, be aware that people have selfishly abused mailing lists like that far too often in the past, and none of the list admins will tolerate you doing it "just this once." You really only need to advertise your party in your geographic region. There are very, very few exceptions to this, and the mature thing to do is to ask list administrators to forward info about your party to their list on your behalf, rather than crossposting on your own.
To see the geographic regions covered by Hyperreal-hosted resources, Go here. In each region's section, you'll find an independently-maintained web site and usually some mailing list info. Some of the sites and mailing lists have calendars. Poke around and find the appropriate method of submitting info. If you do not find the region you want, go to the rave links page and look there for a non-Hyperreal-hosted resource for your area.