Although its user interface has become a nightmare by comparison with Google's, it should be noted that you may be better off with AltaVista when the aim is more to check on term usage than to get a spellcheck suggestion per se. As AV ORs the search terms entered by default (whereas Google ANDs them as well as ignoring stopwords even in quoted strings), you can enter a range of variants of the proposed word in one easy operation, and, near the foot of the results page, you will find:
The number of words that match your search terms: on line banking 25017 ? online banking 600771
Nonetheless, the fact that Google's results page shows the term in context, as well as its rather larger database and access to file formats other than HTML, means that Google is still at present the better general tool for terminological research.
In both Google and Alta Vista, searches can be restricted by domain: in AV use
domain:.uk for Britspeak; to restrict your hits to American English the best bet is to use
site:.edu (Google) or
domain:.edu (AV) since the (unlike .com or .net) the use of the .edu top level domain is generally restricted to the USA (I guess that .mil would also work - depends on your subject area, I guess); however note that in this case AV's usage figures are the total number of hits from all domains, not just the one you asked for.
koreykruse points out that Google offers sundry boolean alternatives under "advanced search"; it does indeed, but (a) it doesn't handle quotes very well which makes it unusable for different versions of multi-word terms and (b) it doesn't break down the number of hits for each alternative, just gives you a total. gn0sis observes, meanwhile that the AV interface is less messy and lower bandwidth if you go via the text-only interface available variously via:
(Raging was originally a short-lived Google-look-and-feel interface to the same AltaVista database but has now been redirected to the old AV text interface).