There’s a package for this: Browser Refresh by Giovanni Collazo. It supports OS X and Windows 7, and all major browsers.
You can install it via Package Control (or manually) and trigger it with super+shift+r in Sublime Text 2.
I haven’t tested it personally since I use CodeKit for this functionality, but it seems popular.
Update:
Windows XP-compatible software
- LiveReload (Windows version is pre-alpha) – there is also a supporting Sublime Text 2 package
- XRefresh – deprecated version of LiveReload (worth mentioning for stable XP compatibility)
- AutoHotKey – example
- VBS script – triggered by a keyboard shortcut
Chrome extensions
- Refresh Monkey
- Easy Auto Refresh
ChromeReloadAuto-ReloadAuto Refresh Plus
Firefox addons
- Tab Auto Reload
- ReloadEvery
IE addons
- AutoRefresher
Note: Browser extensions will refresh at regular intervals, not when you save a file.