FamilySearch and it's partners (findmypast.com and Archives.com) and volunteers (us!) have completed the indexing of six states: Delaware, Colorado, Kansas, Oregon, Virginia, and New Hampshire. They are all searchable by name.
At the time of this blog post, Alaska, Arizona, Florida, Idaho, Montana, Nevada, Utah, Vermont, and Wyoming are all showing 100% completion. Sometimes a complete state gets reverted to less than 100% for various reasons, but this group of states should be the next ones available. After the indexing and arbitration is complete, it still takes a bit more time to prepare the indexes for searching; they say about 10-14 days. Currently, about 30% of the census is indexed. At this rate, they are predicting a complete census by July or August.
Ancestry.com has Delaware, Nevada, and Washington DC completed. They have integrated Steve Morse's one step tool for finding the Enumeration District (ED) into their site for browsing the images.
MyHeritage was the first site to give us a searchable index. Their site says that you can search New York and Rhode Island by name, but a search there clearly reveals that they have not completed all of New York, so it is unclear exactly how much is available. Unlike the other sites that are uploading only by completed states, MyHeritage appears to be uploading each county as it becomes available, but they do not state which counties are finished.
Happy Census Searching!