Suggestion:
Using OpenID would allow a user to be logged-in to http://devevents.uservoice.com from http://devevents.com.

Reduces the number of anonymous suggestions. ;)

Allow for easy replication from this site to others that display event information like CommunityMegaphone, User Group Support Services, INETA, etc.

Getting this error:
'System.Web.Mvc.HtmlHelper<DevEvents.Data.Organization>' does not contain a definition for 'FormatCityStateZip' and the best extension method overload 'DevEvents.Components.Helpers.GeoDataHelper.FormatCityStateZip(DevEvents.Data.Venue, string)' has some invalid arguments

Allow attendees to fill out evaluations online after an event

I tried changing some of the organizer info for the Maine Developer Network and it would not persist the changes.
No error message was provided.

I Signed Up then clicked home - that's what I got.

[NullReferenceException: Object reference not set to an instance of an object.]
DevEvents.Web.DEContext.get_UserGeoID() in D:\My Documents\Community\DevEvents\DevEventsMVC\DevEvents.Web\DEContext.cs:210
DevEvents.Web.DEContext.get_UserGeography() in D:\My Documents\Community\DevEvents\DevEventsMVC\DevEvents.Web\DEContext.cs:194
DevEventsMVC.Controllers.SidebarController.OnActionExecuting(ActionExecutingContext filterContext) in D:\My Documents\Community\DevEvents\DevEventsMVC\DevEventsMVC\Controllers\SidebarController.cs:63
System.Web.Mvc.Controller.System.Web.Mvc.IActionFilter.OnActionExecuting(ActionExecutingContext filterContext) +7
System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +47
System.Web.Mvc.<>c__DisplayClassc.<InvokeActionMethodWithFilters>b__9() +19
System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +192
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +399
System.Web.Mvc.Controller.ExecuteCore() +126
System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +27
System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +7
System.Web.Mvc.MvcHandler.ProcessRequest(HttpContextBase httpContext) +151
System.Web.Mvc.MvcHandler.ProcessRequest(HttpContext httpContext) +57
System.Web.Mvc.MvcHandler.System.Web.IHttpHandler.ProcessRequest(HttpContext httpContext) +7
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +181
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

Create an RSS Feed / email notification for customized searches

It would be nice to allow organizers to see a list of members and also be able to send out mailing list emails to notify of upcoming events or when signup will be opened, etc

Allow event attendees to vote on submitted abstracts

Allow organizers to upload and store relevant documents for centralization. Includes versioning.

1. Removing (leaving blank) zip code in Advance Search defaults to "Location: Within ~75 miles of 19380".

2. Selecting Country == Canada and searching gives same result as 1. (above) Both cases, with default zip, and zip field set to blank.

Suggestion #1:
Make zip an optional field in search;
also, add State/Province as an option
also, add Lat/Long. as option.

Suggestion #2:
For "Within" radius options; "All" full country option.
250 mi may not be enough for CA & TX.

When using my Twitter picture for my speaker profile picture, it isn't being saved. I can set it and it properly sees my photo, but when I go back to view my profile my photo isn't there anymore.

A way out there cool idea is when MS provides an API to create tags have a tag generated for every page so when people print out pages or make fliers for events the tags will be on there to direct back to the events info page.

Create a simple photo gallery feature so groups can display pics of past events.

Add ability to upload a photo to be associated with an event. Such as to show a picture of the front of the building where the event is held.

add ability to include links to twitter, brightkite, facebook, myspace, home.live.com, etc

I could not claim a group using Chrome. I would see the modal and click Join, but nothing would happen. I switched to IE and it worked and I received confirmation dialog.

Allow speakers to upload and store relevant session materials such as PowerPoint decks and demo code. Should be accessible to attendees through the event sessions page

The login defaults my IP address incorrectly and it doesn't show me as logged in. I'm in Canada

Organizers should be able to invite speakers who have opted-in to the speaker registry