Setting quick timer for something is somehow always a bother. Keeping (and finding perfect one in first place) separate software for that seem like an overkill. Phone with timer app happens to be out of charge or lost somewhere. And so on.
Some time ago I happened to encounter nearly perfect solution that requires no commitment whatsoever and offers several related functions - Timer Tab.
What it does
Timer Tab is single page web app with three functions:
Stopwatch starts automatically as soon as you open the site, rest of the bunch needs to be set to desired value and started.
Timer Tab probably earns its name by showing whatever you have running in it as its title and favicon in browser. This eliminates need to actually look at site beyond quick initial setup of whatever of three functions you need at moment.
Since timer/alarm won't make any sense without sound - site does have that. However it chooses to provide it in a form of youtube clip with some church bells. Not my first choice of sound and with Opera's on demand plugin mode it doesn't even play for me by default. On other hand it is customizable (by clicking more link at the bottom of page) and makes perfect delayed rickroll.
Dynamic favicon option is cute, but I find it (unsurprisingly) fuzzy and distracting. For me the tab's title would be enough.
Aside from somewhat strange choice of sound implementation Timer Tab is highly convenient and streamlined web app. Always only a bookmark click away.