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Specifically, one almost like this. Mine is 28-80mm, for a Pentax SLR.
I have wanted to upgrade my SLR camera for many years, but never quite got the money. I'd like to get a DSLR, but I am not sure which camera body will work.
I also have an old Takumar (Bayonet) lens, 1:2.5 135mm, and a XR Rikenon 50mm lens. All of these fit onto my Pentax.
Your Promaster Pentax-mount lens will work with any modern Pentax DSLR*. Your older manual Pentax lens will too, but you will need to push a button to take a meter reading - they won't meter continuously. That's also the case with the XR Rikonon.
Some older Rikoh lenses are dangerous to use on Pentax DSLRs, but this one will be fine.
But, these are also not very high-end lenses. The kit lens you can get at low cost bundled with any new DSLR will be of much higher quality than your zoom, and probably of the two prime lenses too. Pentax made some great Takumar lenses, but the one you have is one of the lower-end options, and while it's fun, it's not great. And, finally, the Rikoh lens is generally well-regarded for what it is, but consider that it can be had for about $10 in the used market.
Pentax makes nice cameras, and they're worth considering as you look for a DSLR, but I wouldn't factor these lenses very heavily into that decision.
* Except the medium-format 645D range, which requires lenses with a bigger image circle anyway.
Assuming all of your lenses are in the Pentax KAF mount like the example you linked they will all work with any Pentax DSLR except the medium format 645 models.
The Samsung GX-10 and GX-20 were virtual copies of the Pentax K10D and K20D, respectively, and will also work with your lenses. The Samsung GX-1s (Pentax *ist DS2) and GX-1L (Pentax *ist DL2) also used the Pentax KAF mount. These models were introduced between 2005 and 2009 and are no longer available new, but you might find a good used copy that will work with your lenses.
In the larger view, though, your current lenses aren't really that good compared to even the budget lenses offered today. Unless you're operating on an extremely tight budget and are looking for a DSLR that is a couple of generations old to work with your current lenses, you should probably consider other options that may give you the features and performance you want. Pentax may well be the answer for you, but don't sell other options short just because you already own a couple of old lenses that aren't anything special.
As other answers have noted older Pentax K-mount lenses will fit on new Pentax K-mount bodies and none of your old existing lenses are of such high quality that people pay big money for them on ebay and the kit lenses from other manufacturers' lower end DSLR line might be better. So why am I posting another answer?
I went through a similar decision process when I upgraded from my Pentax K-1000 and Pentax wound up being the best choice for me. Why:
At the cheaper end of the DSLR spectrum Pentax offers weather sealed bodies (K-series) and lenses (some of the DA WR series). Pentax 'kits' typically include the weather sealed lenses. This means I don't worry whether the weather might include rain and whether I should take my camera, I just worry about whether my battery is charged. Other manufacturers tend to only offer weather sealing as a feature at their professional and prosumer pricing tiers.
Pentax's cheaper cameras provide image stabilization in the camera body. This means old manual Pentax lenses I owned before upgrading got upgraded for free.
Pentax's cheaper camera models also offer 100% viewfinder and two dials. Like weather sealing, other manufacturers tend to add these as features at their professional and prosumer pricing tiers.
Most importantly, backwards compatibility means I simply have more lenses to choose from. For example, my old Tokina zoom provides a macro feature. The old Ashi Optics 50mm offers a wider aperture than my new zooms. Weather permitting, this means I have more shot options.
To a very large degree the options for new lenses in the Pentax system are similar to the options for upgrading lenses in other manufacturers' systems. At the point where there is significant divergence, the cost of buying a different manufacturer's low end body is often about the difference between getting a really good price on a magnificent lens and getting an average price or between adding two pretty nice lenses to my bag or one.
Pentax's DSLR's shoot DNG as RAW format rather than a proprietary file format as is common with other manufacturers. DNG is a stable open specification used supported by many commercial and open-source RAW editors. This makes choice of software a bit less complicated.
In your case, you can buy better glass than your old 135mm f2.5 lens. But it won't come as a kit lens. Looking on BHphoto: to replace it with a new roughly equal lens will cost around $200. To replace it with a probably better lens around $450. To replace it with an autofocus lens about $1000. Incidentally, your lens has a reasonable rating on Pentax Forum and I'd bet people are still happily shooting with it. There's also a review page for your Promaster lens.
In the end, it's all tradeoffs and what was the right choice for me, may not be the right choice for you or anyone else.
The Sony e-mount "mirrorless" bodies will take ALMOST any lens made if a suitable adaptor is available - and many are*. The newer e-mount bodies are not overly cheap but some extremely good models are available 2nd hand at attractive prices. The NEX3 series are "reasonable" and the NEX5 are "surprisingly good". I have an NEX5N and NEX5T (both bought 2nd hand) and am very pleased with the results and capabilities. Compared with a "real" SLR with more physical controls the lower end mirrorless cameras are more annoying to use, but get reasonably responsive once the brain grows used to their control systems. (My Sony A77 SLT with 2 control dials and more buttons and other controls than you can easily count is vastly superior 'when things happen very fast' but otherwise a low cost mirrorless can be good value for money.
The cheaper adaptors provide manual control only - manual focus and camera guided aperture control in A & M modes. When used in "A" mode at preset aperture there is minimal difference exposure wise from having a full auto-exposure lens.
Fully auto adaptors are available for a limited number of other lens systems but the cost largely makes them unattractive for low cost entry points.
