Hey Sierr - was wondering when someone was going to ask about those.
Technically, I'm not so sure Jagex even allows it, which is why I've held off on them. Let me try to explain...Stat/Goal signature data is received directly from the RuneTrack database that is updated every night at the system update (or if manually updated via your User Profile). So say if you log in right now and gain 50K runecraft xp, then log out. This 50K gain won't show up on your Runecrafting Goal signature until either the system update or you click the "Update Signatures" link in your User Profile.
Additionally, consider that there's only two data types needed to calculate the Xp Remaining - one is the Goal Xp you set for yourself, the other is your most recent recorded xp. The Goal Xp is set in the signature image URL itself, and the most recent recorded xp already exists in the RuneTrack database. All the signature has to do is subtract one from the other to calculate the Xp Remaining.
Now with all of that in mind, say I wanted to make a Daily Xp Gained signature. This would again require two data types that the signature would need to know - one is the xp at the start of the day, the other is your Current Xp. The xp at the start of the day is easily retrieved from the RuneTrack database.
But here's the issue - where does your Current Xp come from? Obviously the only place it can come from is directly from the RuneScape hiscores. This means that *every single time* the signature is viewed, it would need to grab your current xp directly from the RuneScape hiscores. Now this isn't a problem at all for RuneTrack - but Jagex has said in the past that they forbid excessive automatic updating off of the lite hiscores. Having a bunch of signatures which automatically update off of the hiscores each time they're viewed (like every minute on busy forums) would certainlly fall into the category of excessive.
Andrew Gower said on the RuneScape Forums a while ago that automatic database updates shouldn't occur more than every 24 hours, though since then Jagex has been more lenient in allowing a database update 4 times a day, according to Tip.It sources. However, they haven't said anything about allowing automatic updates every minute yet.
Although I don't think it's exactly what you were looking for, here's an example of a signature service which goes against Jagex's apparent policy of not allowing automatically updates in retrieving hiscores data upon each page refresh:
Now of course no one really says anything against them because most don't understand what those signatures are really doing - but I'd like to keep RuneTrack as well within the rules as possible.
I'll try to get some official confirmation on all this though, and can look into it if I get the green light.
Edit: Now of course the "Stopwatch" idea on the RuneTrack site itself we were discussing earlier would be within the rules.
While both that idea and the signature idea are essentially the same I think in tracking your last "xp session", the difference is that the "Stopwatch" page would only be updated when that specific page was refreshed because you or someone wanted to know about it and thus manually activated it by refreshing it. However, in signature form, the signatures would be refreshed/updated countless times per day on forum pages by people who don't even know or never had the intention of updating your RuneTrack session tracker.
All a bit confusing I know, but Jagex really has been unclear on this, which puts all of us who deal with this type of thing in an odd situation.