A trick I have used, well not exactly a trick is to use Google for my searches.
Kinda like if i was searching for blue widget, I would type BlueWidgets.com into the
google browser. If I get no results, then I would bookmark that page and
if I decide to purchase, I could at a later time/date knowing that my search is
secure-as secure as a query could be.
I too have had many a domain snuffed for waiting. As someone pointed out
earlier, dont search without funds handy. I for one stopped trusting all registrars, or domain spinners for ideas unless I was fully strapped, prepared to buy...not for just mere search sakes!
Shorty does have a nice script which has resulted in good domain search safety. Another trick I personally use is if I am searching for a domain on say, A Godaddy, or Network Solutions- I never search using the extension I intend on purchasing.
Once again using BlueWidgets as an example. I would search for BlueWidgets.mobi as opposed to BlueWidgets.com. .Com being the favored extension, my search for the .mobi would let me view whether the .com was available and since the .com wasn't entered as an "hard inquiry", the search for the .com wouldn't be logged.