I use bangs very frequently and quite like them. Probably the ones I use most are !gh to search github or !npm to search npm (although npmsearch.com is often more useful). One thing I wish I could do was combine the first-result bang (!) with other bangs (like !gh). That would translate into "take me to the first result on github for these search terms..."
Technically I suppose it's possible to "scrape ahead" and get the top result in the background before redirecting the user, but some sites change search results based on your profile/behaviour so it could be inaccurate. It may also be against those sites' terms and conditions.